The actress, who shot to fame as the Doctor's new sidekick Clara in the BBC1 sci-fi drama, admitted she finds being alone with another person nerve-racking.
Coleman, 27, blamed her shyness on moving at the age of 14 from a tiny secondary school, where there were just eight pupils in her year, to a nearby private school.
She told the Radio Times: "If I'm with a group of people I'm okay, but actually I'm quite a nervous person if I'm just one-to-one with somebody.
"I've got a lot better as I've got older. I think it was going from eight people in a tiny, tiny school to being surrounded by loads of people. I shrank away, surrounded myself with quite loud friends. I'd never been on a date in my life ever because the idea of just being sat with one person..."
The former 'Emmerdale' actress, who is in a relationship with Game Of Thrones actor Richard Madden, said: "I'm making myself sound socially inept here and I'm absolutely fine in a group of people but I am quite shy."
The actress, who grew up in Blackpool, said of her new-found fame: "I have a really cool job and get to do these crazy things and you do have so many 'pinch me' moments. I've just been sent emails with pics of the Clara doll."
She said: "Clara is probably the closest to me that I've ever played - especially over the last few years - and I find that hard. Doing an accent is much easier."
She hinted about the series finale: "The Doctor's greatest secret is revealed, all of his friends rally round to protect him and we finally understand why the Doctor has met Clara so many different times."
She added of her co-star Matt Smith: "His first advice was never Google yourself and, now that I've got a three-month break, he said take your time and choose your next role carefully. I've read loads of scripts but nothing I'm really in love with."
BAFTA paid tribute to Doctor Who on the red carpet this week...