Now the Pollok-born actress is back treading the boards, this time playing the challenging role of an OCD sufferer in Takin' Over The Asylum, running at the Citizens.
But why the long break?
After all, Paterson's name was once synonymous with theatre in Scotland.
She was part of the radical theatre group Raindog, which produced some of Scottish theatre's most innovative work.
And she won acclaim as a director of The Slab Boys trilogy.
"I've been offered a lot of theatre, but I found it really hard to leave my family, to orchestrate it to come up here," explains the actress, who lives in Chiswick in west London with partner Claudio.
"But when I was offered Takin' Over The Asylum I thought, 'If I don't do this now I never will.' It was a case of saying (to the kids, Louis, 15, and Ruby, 10) 'Give me three and a half months of my life to let me work on this'."
And they did. But there's another reason why Caroline, who starred in EastEnders as Ruth, (the partner of HIV sufferer Mark) was keen to join Takin' Over The Asylum.
Caroline appeared in Donna Franceschild's original 1994 BBC drama series, from which this play has been adapted.
Caroline, 47, was 24 when she played the role of Jane in the story of a hospital radio station boss and the confused characters who inhabit this world, played by newcomers such as Ashley Jensen and David Tennant.
"When I looked back at the series my first thought was that I looked great," she says, with a wry smile. "And wondered why I couldn't have enjoyed how I looked back then."
The story is set in modern times and features a range of mental health issues. But Caroline points out that there's a lot of humour in the play, too.
"I think Donna has really made a great attempt at turning the series into a play," she said.
"It's brilliant. And there's a real subtlety about the writing in that she doesn't go banging on about mental illness.
"Plus, I've got a great part. My character, Rosalie, has a problem with OCD. She worries about germs.
"She makes lists constantly. She's had trauma in her life and you get to find out what's brought about this disorder."
Caroline, who had a stint in BBC soap River City playing a drug addict, has been studying the condition.
"I've been reading up on it, and I've got a friend who as soon as you've had a cup of tea has to take the cup away and wash it.
"It's a fascinating subject. But it's a very difficult condition to get rid of," she said.
The role also offers another delight.
"I get to go back to the Citizens Theatre," she says, beaming.
"I worked at the Citz as an usherette when I was 16. I have a great history there. I loved it."
Caroline, whose grandparents had a Vaudeville cabaret act called York And Morgan, and broke into theatre via a YTS scheme, says the prospect of appearing on stage is both exciting – and daunting.
"It's been a long time, and I'm a bit nervous, yet I can't wait. I get to work with a great bunch of Scottish actors," she says of the likes of Iain Robertson, Martin McCormick and Molly Innes. "But I do feel like the new girl in school."
Will her kids come and see her in the play?
"Yes, I'd like them to. They've never seen me in theatre. And they'll get to watch it, to come backstage, to enjoy the whole experience.
"TV doesn't impress them. My teenage son said to me, 'Don't get a part in Holby City. (Which she did, in 2010). It will be so embarrassing for me!'
"It's not like they're saying 'I'm so proud of you, mum'."
n Takin' Over The Asylum, the Citizens Theatre, February 14-March 9 and the Lyceum, Edinburgh, March 13-April 6.