The Notting Hill star is set to play the Diving Bell And The Butterfly star's lover in the true story about a World War II veteran seeking therapy for post traumatic stress disorder, filming in Detroit.
Gina said: "My attitude is to just try and approach it like you would any other job... otherwise it can be a sort of barrier. So I try to ignore the fact I might be excited or nervous and just behave like I would if it was anybody else."
The Line Of Duty star feels there is a boundary between being an actress and a showbiz personality and she has no interest in crossing it.
"I think I've been aware of that always, and I don't think there's been a huge change there. I think it's a skilful thing to negotiate, and I'm not sure I'm that skilful with it, which is why I've avoided it!" she laughed.
"It suits me to concentrate on the work and hopefully other people will do the same."
But she still gets recognised in the supermarket on occasion.
Gina said: "I used to often get people think they know me, but they didn't quite know why. Whereas now, if you're standing still in a queue or something like that, people begin to talk to you.
"And people are usually really supportive and lovely, so it's certainly no hardship. It feels rather nice actually."
:: Gina plays bubbly mum Pauline in new BBC sitcom Hebburn, which begins on BBC Two on Thursday, October 18.