The former EastEnders actress will make her debut in the stage production when it begins a tour of the UK later this month.
Calendar Girls tells the true story of a group of Women's Institute members who appeared in a nude calendar to raise money for charity. The stage version sees its female cast members stripping off with only well-placed objects to protect their modesty.
However, Dean told the Daily Express: "It's been so cold in rehearsals that I haven't taken my coat off, let alone my bra! It's something new for me as I've never taken my clothes off on stage before. I just hope there will be some cheating bits and I will certainly need bigger buns than normal.
"Mind you, my character is the vicar's daughter who is an organist and I play the piano like Les Dawson so I'm more nervous about playing the instrument than getting my kit off!"
> Gemma Atkinson re-shoots Girls poster