The actor, who plays Jason Grimshaw in the ITV1 soap, welcomed daughter Scarlett in 2008 with his former co-star and now ex-girlfriend Tina O'Brien.
"Scarlett's the best thing that's ever happened to me," he told The People. "I'd always wanted kids but I never thought I'd be a dad so young and I was terrified when I first found out I was going to become one. I remember thinking to myself, 'Ryan, this is it, you've got some serious growing up to do'.
"I'm far more conscientious than I used to be because when you've got a little 'un you have to constantly keep an eye on them. She's only coming up to three but she's wise beyond her years in some of the things she says. She's like a little old woman.
"I spent a week with her on holiday in Spain earlier this year which was really special. It was great being able to have that time together to bond. We had a little villa near Marbella and, to be honest, we barely left it. We just sat and played and enjoyed the sunshine, it was really special."
Thomas added that he isn't looking for a girlfriend at the minute because his daughter is his number one responsibility.