Pete Doherty on heroin, life in Paris and his new film

In a Paris attic apartment decorated like a 19th-century dandy's den, a rottweiler snores on a velvet couch and dozens of candles give out a half-light. Pete Doherty kicks an apple core round the living room rug and chats in broken French to a friend on his cracked iPhone. Balzac novels are stacked high on the window ledge.

This is Paris Pete, the rocker who now sings solo as Peter Doherty, writes poetry, paints and has made his debut as a French arthouse-cinema actor. For years, the Libertines and Babyshambles frontman was London's most notorious rock-star addict. The baby-faced, sallow-skinned, tabloid whipping-boy was kicked out of his first band, served three stints in prison for drug possession and breaking into bandmate Carl Barat's home, dated Kate Moss and sparked handwringing about wasted talent.

Doherty moved to Paris four years ago, part of a long, difficult quest to get clean. But more than a decade since the Libertines burst on to the British music scene, he still can't get through the day without heroin. Paris might not be the obvious place for a rocker to kick his habit. Jim Morrison of the Doors – who, like Doherty, came from a strict, military family – was found dead in his bath not far from here, aged 27. But Doherty, 33, as bouncy and optimistic as he seems vulnerable, is hanging on. He has got this far and is still standing – just.

After the warm handshake and the Parisian kiss on both cheeks – Paris music insiders praise his "gentlemanly" politeness – Doherty settles in an armchair in the bedroom and sips tea and smokes. My phone rings – it's my mother. "You better take it, or she'll be worried," he urges.

Family for Doherty is still a raw point. Tattooed across his neck is Astile, the name of his seven-year-old son with singer Lisa Moorish. He has never lived with Astile and once avoided seeing him because of his addicted state. Doherty's own father, an army major, who has called his son a "pathetic, limp figure", refuses to see him until he stops the drugs. A sadness crosses Doherty face. "I'm still in touch with my mother," he says, as if to cheer himself up. "She came to Paris for the premiere of my film, and do you know what?" His eyes widen in surprise. "She loved it. It meant a lot to me because I know she wouldn't hesitate to tell me if she thought it was naff."

Doherty says he always wanted to act. But in his first film, Confession of a Child of the Century – based on the novel by French 19th-century poet Alfred de Musset – he admits he is virtually playing himself. His character falls in love but, he says, "from that vulnerable position, sets out almost with military precision to destroy it all" in order to "empower himself", and turns into "a bit of a git".

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The director, Sylvie Verheyde, who occasionally wanders in and curls up on the bed, has become his surrogate family in Paris, a sister-figure. "My mum loves her," Doherty says. "She told her: 'Thank you, you saved my son's life.'" This is Verheyde's apartment – Doherty sometimes hangs out here, but has his own rented flat in the west of Paris in a posh, quiet neighbourhood, the last place you would expect to find him. But quiet is not a bad thing, he reasons.

Despite the film's harsh treatment from French critics, Doherty still enjoys cult hero status in France. He is revered as the quintessential British rock star, a misunderstood romantic. The ultimate compliment is the constant comparison with Serge Gainsbourg, France's legendary, heavy-drinking, musical poet-provocateur. Doherty's Old Albion Englishness – the William Blake allusions, the pork-pie hat, the "tickety-boo" expressions – that seemed a bit fantastical at home are lapped up in France. He plays up to the Englishman-in-Paris tag. "I go into the newsagent and say: 'It looks like rain today.' And they're saying: 'You can't talk about the weather, this is the country of revolution!'"

The only person who doesn't really feel France's obvious love towards him is the brutally self-punishing Doherty himself. "I remember the first time we came to France with the Libertines, the French magazine Rock & Folk just said on its cover: 'Danger: Wankers!' I always felt a little bit of hostility, as if the French stand back with arms folded and say [he puts on an 'Allo 'Allo accent] 'Ow dare you call yourself Libertines? You do not understand what it is to be a libertine.'"

Doherty glances at a picture of himself on the cover of a French magazine that is lying on the table. Of his early fame in London and the madness that came with it, he muses: "For a little while maybe I did fall for my own mythology."

He tends to think people dislike him. "On a number of occasions here I've met individuals who've taken it as a personal affront just for me to have stepped into their company." He says sometimes people are even "offended" that he is on the Paris metro and he feels he has to prove himself. "I'm not really a fighter but I've never backed down from anyone in Paris. I feel I can't. In London I'll just run because I'm not going to fight 50 Wolverhampton Wanderers fans. But in France, I feel more related to these lads who are angry at me because they're taller and better-looking than me but they don't get articles written about them, and they have to graft."

He seems both to hate and to be unable to resist what he calls "my bad reputation and all that goes with it". But he nurtures it, embellishes it even. Recently he made French headlines for supposedly being banned from the French railway, SNCF. He had written on his blog that he was desperate to see Noel Gallagher in Toulouse and could anyone lend him and his mate a car. He couldn't go by train as he was "in discussion with SNCF regarding my accountability for a missing trolley-load of staff uniforms (gaberdine wool, mind you), cold meats, cutlery".

He grins and feigns outrage. "A pair of shoes had been left on the platform. And I was in a bit of a state, I was basically in these hotel slippers, and I was late for a train at Gare de Lyon. So I just put these shoes on. It was only afterwards as the train was pulling out I saw a ticket inspector with no shoes coming down the platform. It was comic more than anything. I posted them back. I just changed the laces from black to pink."

(Later, I call SNCF. A spokeswoman sighs. "We don't ban anyone from trains," she says, adding that she has no idea if there is any truth in what Doherty is saying.)

The deal was that Doherty would get clean before filming Confession of a Child of the Century. He went into a clinic but failed, so he stuck to the rules of always arriving on time and sleeping at night, but still used heroin, albeit at his minimum. "If I had a good whack in the morning then that would be 12–14 hours and then I'd generally have a little bit of something for insurance, just to keep my mind at ease. It's a psychological thing more than anything."

He describes debauchery as "the lust and freedom that comes from complete freefall, but unfortunately with that descent you generally end up flat on your back in darkness if you completely let go with nothing to hold on to. No handrails: I always thought that was the definition of a libertine ..."

He looks me in the eye: "It's not actually that exciting to be fucked up all the time. The rush that you get from having a good night's sleep is so exotic: to feel powerful and clean, capable and potent, as opposed to washed up, impotent and mute. It's like if you sing and you've been up for four nights, your voice is puny and has no power. The difference when you've rested and had a banana in the morning, it's outrageous! You can scare yourself sometimes with what a bit of healthy living can do."

Does that mean he now goes to bed early? "No. It means that I can completely see the necessity of having a bit of self-control now. It's going to be the only way to salvation for me, to give myself some clean time and take a proper run at it."

He adds: "I've started the warm-up for the run at it. I'm going to give it a good go, but ..."

One of the problems is that he finds it so difficult to show himself any kindness. "I'm not a suicidal person at all, but on paper it seems that I am. I think I'm really quite horrible to myself in many ways. You always think it's going to be fine, the body will repair itself. There will be another chance. But I'm 33 now. The body won't keep repairing itself. You know when you can flick a coin and catch it on your elbow, and flick it up and catch it on the back of your head? And then you can't even catch it with two hands any more. You realise something is wrong ..."

He tells a story. "The other day I really hadn't slept since last week's gig at Brixton Jamm, and I was coming home on the Eurostar. I fell asleep for an hour, woke up and didn't know who I was. I was completely devastated and I burst into tears. The train was parked up. Apparently I'd been shouting in my sleep as well, so they'd just left me. I knew I shouldn't be crying. The train manager said: 'What's the matter?' I told him straight: 'Look, I don't know who I am, I don't know where I am.' He said: 'You're Peter.' And I was going: 'No, no, I'm not.' Then bang, everything flooded back. I got my bag and ran off. But it was a really horrible feeling and I can imagine it in a few years just lasting longer and longer."

There's a pause. "Argh!" he shrieks, jolts and grabs his calf. Are you OK? "Yes." A while later he gets another sudden shooting pain in his jaw.

How will he get off the drugs? "Being in Paris is me making a statement of intent. It's like saying: 'I'm trying.' Because it's so difficult to get decent gear over here. And I've got to make an effort now for my family, my son, my father. I'm not 23 any more, I'm 33, for Christ's sake! And the time has come, the walrus said, to speak of many things, not just smack."

One of the things he dreads talking about is his co-star in the film, Charlotte Gainsbourg, daughter of the French rock god Serge. He refers to her as the French "royal family" and "this other-worldly entity". Their awkward dealings while making the film seem to have been like some terrible family therapy. He was fascinated with her dad. She, still hugely protective of her father's legacy and troubled by his death, seemed to take against Doherty. Then he describes a sudden "tsunami" of bonding between them, with "heart-to-hearts" about her father. But Doherty read her diary when she had "nipped to the loo", and found a page slagging him off. He confronted her and she ripped the page out. Things went cold again. "It just all ended really weirdly. She said: 'I spoke to my mum's friend and she said your hobby is breaking up families.' What kind of talk is that? I don't want to break up families. I'd like to make a family ..." He leaps out of his chair, paces, says he's getting "uppity" because he has realised that he misses her a bit.

Another French royal whose path he crossed was Carla Bruni, when he was invited to some music sessions at the house she shared with Nicolas Sarkozy, then president. Bruni and he "connected" through their shared stage-fright. "She was surprised to hear I actually have a lot of trouble going on stage. Nervous isn't the word, I get twisted. And she says it's the worst place in the world for her to be, she hates going on stage, especially in France because she feels that people hate her, she says they're out to get her basically."

Her house was "a really strange scene, where you've got a guy with a submachine gun on each door".

Did he meet Sarkozy? "You're joking, aren't you?" he laughs, blaming his bad reputation. "She told me she took him to see Bob Dylan. She had the harmonica that Dylan gave her, and apparently he was like: I don't want to meet this guy, who is he anyway?"

But he found their obvious love for each other staggering. "All the time, I was aware that she's just devoted to this guy. She said that in another world, if he'd been a farmer and she'd been a bakery girl, they still would have been together."

Doherty, who once described prison as "a tiny room, just sat there all day", says the best thing about Paris is walking across the city late at night: "You don't meet anyone." He's solitary, he says, but still lives under the shadow of management and minders. Our photographer arrives to find he wasn't expected. A press officer suggests there will probably be no photos as there has been "no grooming". This seems absurd given Doherty's persona. Doherty agrees to overrule them, and not only poses politely for pictures, but gets his guitar and sings for us.

As night falls Verheyde shuts the bedroom door and gently persuades him to do one more bit of film promotion. "I'm 33!" I hear him protest. He wins, emerges in his coat, whispers "Au revoir petit chien" in the rottweiler's ear, and, in one last unspoken comment on fame tucks the magazine cover of himself under his arm and walks out into the night.