The actress, who was voted out of Dancing on Ice last weekend, said that she could play any one of the group's five members.
Ellison told The Sun: "I'd love to do more West End. They are doing a new Spice Girls musical so I'd love to be a part of that.
"I could play Baby [Emma Bunton], I've got the boobs for Geri [Halliwell] and the hair for Mel B as well.
"I'll tell you what, I'll play a different one each night!"
Ellison's previous West End credits include roles in Calendar Girls and Chicago.
The Spice Girls musical, titled Viva Forever, is produced by Jennifer Saunders and Judy Craymer.
It is expected to open later this year.
> Dancing on Ice semi-final - in pictures