LONDON — TV comedy scribe/performer Jennifer Saunders (“Absolutely Fabulous,” “French and Saunders”) will pen “Viva Forever,” the previously announced stage tuner from “Mamma Mia” creator/producer Judy Craymer.“Viva Forever” is based on the song catalog and “girl power” ethos of Nineties U.K. pop sensation The Spice Girls. According to press reports, the show will have entirely fictional characters and will be neither a bio-musical nor a tribute show. It will be Saunders’ first time as the writer of a tuner. “It has a glimpse of the underbelly of TV talent shows, an invented show, and a little bit of comedy romance,” promised Ms Craymer. Creatives and cast have yet to be set.