The former Coronation Street actress has teamed up with Jon Culshaw for a new eight-part BBC One series which sends up stars like Cheryl Cole, Anne Robinson and Ant and Dec.
Stephenson told This Is Hull: "I think one of the most difficult acts to learn was Davina McCall. She doesn't have a particularly strong accent and has a fairly regular presenting voice. She has a vocal quality like mine, so it is more about her mannerisms.
"We're not cruel to anyone, though. I'm looking forward to seeing it on TV."
Stephenson started entertaining audiences with her impressions when she was a teenager, but had not found a mainstream medium for her talents until now.
She explained: "I got into it through my dad. He would write and coach me, while my mum would make costumes. Although it would be hard travelling all over to perform, it was fun.
"It got to the stage though where there wasn't much happening for impressionists, so I decided to go to drama school and from there got the roles on Coronation Street and Bad Girls. Going back to impressions, it feels like I've gone the full circle."
The Impressions Show with Culshaw and Stephenson begins on Saturday at 9.45pm on BBC One.