Once upon a time, there was a popular TV show about a gal in her thirties making her way in the big city. She had funny experiences with men, and fraught ones too, and every so often would sit down with her girlfriends to hash out exactly what was so great about being single. The show ran for seven years, and its playful face of feminism helped change the world. It certainly changed Kim Cattrall's life.

She was a teenager growing up on Vancouver Island when she first saw The Mary Tyler Moore Show. It spoke to her. "I loved that fantasy of being single and having a job that you love and a workplace filled with people who are eccentric and dysfunctional," she explains. "That really captured my imagination."

In time, life taught Cattrall not only that she could make fantasy her reality, but that the two sometimes twist together like dancing strands of DNA in a high-school science textbook.

She is perched at the moment on a banquette in the pocket-sized in-house café of a photo studio on the west side of Manhattan, winding down from a long day spent half pretending, for Chatelaine's cameras, to be Samantha Jones, her onscreen alter ego from Sex and the City.

Only a few minutes ago, Cattrall was all jutting body parts for the camera – breasts and elbows and hips, oh my – but now the mascara has been wiped off, the hair extensions tucked back into the stylist's tool kit, the outfits already on their way back to Toronto. She is relaxed and natural and looking a youthful 51 in jeans and a loose-fitting cream-coloured sweater.

In a surprisingly gentle voice, Cattrall is trying to parse exactly what SATC bequeathed to women (other than permission to spend far too much on footwear): "Being single always had such a negative connotation when I was growing up. If you were single you were unwanted, you were unattractive, you were undesirable," she notes. "I felt that. If I didn't have a boyfriend, I didn't have an identity."

While SATC originally aired only on HBO, in syndication it has been everywhere, pulling in new audiences of giddy single women and making old fans feel as if it never went away.

When the post-feminist series signed off in February 2004, Cattrall resisted pleas for a feature-film version, saying producers had provided her with neither a script nor a salary offer that was satisfactory. She fought it out. (And even Sarah Jessica Parker, SATC's alpha earner, has acknowledged Cattrall's battle was justified: "If I had thought it was any of my business at the time," Parker said recently, "what I would have said is, 'Isn't it okay for Kim to think that the money wasn't right?'")

And now, fans finally have their movie. For Cattrall, though, the four years leading up to this point were an intense time of separation from the series, full of the highs and lows that come to many women (and men) when they crash into their fifties. That's one of the reasons – other than money – she says it took so long to acquiesce to requests for a movie; she needed to take stock of her life.

"I look back at those four years – I can't believe I got through it," she says, with a faint shake of her head. "My job of eight years was coming to an end, and I was going through a really rotten divorce, and my dad was diagnosed with dementia, which was the cruelest thing of all." She was also playing jack of all trades with her Toronto-based company, Fertile Ground Productions; producing a documentary and a companion reference book, Sexual Intelligence; and writing an advice book for young adults, Being a Girl: Navigating the Ups and Downs of Teen Life.

"I wasn't really thinking about anything other than what was right in front of me, and dealing with so many personal and professional conflicts, and I think that's why it was so important for me to go home and be around people that I had known for decades. People came back into my life that I hadn't seen for a very long time."

Home is still Vancouver Island, where her middle-class British family – her father was a builder and ex-officer of the British Army, her mother a housewife – settled after leaving post-war Liverpool in the late 1950s. There, no longer at the mercy of producers, Cattrall spent time with her family, helping her dad.

Home is also Toronto, where Cattrall still has many old friends from the days when she was part of the city's 1970s alternative-theatre scene. It was a world away from sleepy Vancouver Island, but her family cheered her along, driving halfway across the country to Toronto to see her star as Janet in the The Rocky Horror Picture Show.

With a few plays under her belt, Cattrall headed south, where she found a home in the belly of the Hollywood beast as an anonymous pretty face on TV series like Starsky & Hutch and Charlie's Angels. "Victim of the week," she quips now. "One week I was raped, one week I was blind, one week I was shunned, one week I was left at the altar."