This is the story of Janie Ryan and her Ma, Iris. Born in Aberdeen in the early 1980s, her Ma having "been tae London and got herself preggers", Janie is initiated early into the ways of the fishwife  fighting, falling out, and moving on. Homes are places to pass through: rare B&Bs that accept DHSS, but lock their doors between 10.30am and 5.30pm, leaving Janie and her Ma to pass the hours in shopping centres, playgrounds with one slide, or concrete high-rises. Fathers are absent, violent or passive ("Leanne, love, fix us a snakebite"). Skin is "the colour of Spam" or "like wet candle wax". Food is grey  frozen burgers, frozen chips, cans with white paper labelled only "stewed meat".

This is the poverty trap writ large, the authentic working-class experience in all the mess and glory of the giro queue, drug and booze dependency, and gallows humour. For all the shifting locations, relationships and casual jobs, nothing changes  nothing is ever overcome. Iris, midnight flitting with her little girl from one damaging situation to the next, steadily loses her will to fight. But then there's Janie, and even in her wanton teenage years  staggering around Great Yarmouth, shagging and boozing  she knows she's better than this; she knows she can get out. Kerry Hudson's early life was like this. What a brilliant thing to turn the chaos and trauma of a hectic childhood into a debut novel as colourful, funny, joyful and compelling as this.

Janie Ryan, the latest in a long line of Aberdeen fishwives, swears, weeps and rages her way through a debut that traces her life from birth to 16 in a world filled with love, poverty and violence.

Tony Hogan Bought Me An Ice Cream Float Before He Stole My Ma (it's a terrible title) gets off to a technically wobbly start: a nameless and all-knowing newborn narrates her first weeks before the narrative voice inexplicably regresses to the more limited (and all the more engaging) voice of a toddler who grows into a clever, vulnerable child. Janie is poor and neglected, but finds delight in tangerine-coloured curtains, Connect Four and a red umbrella. She curses like a sailor, and tries to make coffee for her hung-over mother, Iris, in a toaster because she knows she's not allowed to touch the kettle.

Iris, a resourceful optimist with an endless appetite for a fresh start, takes Janie on a picaresque adventure around the UK, from Aberdeen to London, Canterbury to Glasgow, through a series of bedsits, bed and breakfasts and council flats. Hudson's skill is to make us care about these characters  we worry about their money problems and when Janie reports that her mother needs to go for "long sleeps", we feel for her in her depression. And who wouldn't be depressed? This is a world where the food runs out by Thursday and hitting is something people's daddies just do.

Some scenes are painful to read: the domestic violence, the neglect. Tony Hogan is no hero  and yet, of course, Iris forgives him and welcomes her swastika-wearing thug back once too often. Janie is left alone, locked in her bedroom to soil herself and cry herself to sleep, because Iris wants a night out on the vodka. But despite the grinding poverty, drug addiction, alcoholism and violence, this isn't a relentlessly dark book. It's an honest one: honest about the things that go wrong and about the lives that people who don't often get to be the stars in fiction really do lead.

The novel is also honest about family, about the fierce love between Iris and Janie, about the loyalty between Iris and her flawed, tragic brother Frankie, about the necessary, desperate friendships formed between women in dire straits and about growing up. These relationships are real and heartfelt, carried along by stunning, earthy dialogue that captures the rough poetry of daily speech.

The last third of the book slows a little. The family settle in Great Yarmouth and Janie enters her teenage years. The tension brought to the story by Iris's partners  the frightening Tony and shiftless Doug  dissipates. Some pace is lost because the main driver of the episodic lurch from one bad set of circumstances to the next  Iris  is washed up, tired out and done in at a mere 36. Although Janie, with her well-observed teenage voice (according to her, all her mother's problems could be solved by a haircut and an advert in a lonely hearts column), continues to charm us, from this point the narrative never equals the crabby innocence of her younger self.

Still, everyone has to grow up, and Janie's adventures with drugs, alcohol and sex start to echo her mother's. The meandering storyline resolves itself into an urgent question  is Janie doomed to live a life just like Iris's? Janie's emerging sexuality, her friendships and all those memorable firsts  drink, drugs, boys and church services  are engaging, but this part of the novel treads a worn literary path. However, though Janie discovers  of course  the magic of books, Hudson avoids the usual sentimental clichés and gives us, without a shred of hipster cynicism, the hope and tough warmth for which she has such a sharp eye.

 Jenn Ashworth's Cold Light is published by Sceptre.