The actress has been cast as a New Jersey high-schooler who gets sent back in time to 13th century Verona and finds herself trapped in Shakespeare's Romeo And Juliet.
Gillian Anderson will play Gillan's mother and a nurse in Verona, while Misfits actor Robert Sheehan is the school nerd who becomes Brittney's Romeo.
Baddiel, who penned this year's Omid Djalili comedy The Infidel, will begin shooting the $7 million production next May.
Producer Arvind Ethan David told Deadline that Baddiel's film is being touted as "Shakespeare In Love meets Clueless".
"We both love literate teen comedies and we wanted to do our own version," he said. "After all, 10 Things I Hate About You was based on The Taming Of The Shrew just as Clueless was based on Jane Austen’s Emma and Easy A is inspired by Nathaniel Hawthorne's The Scarlet Letter.
"And what is Twilight if it's not Romeo And Juliet with vampires and werewolves?”
Gillan can next be seen in the Doctor Who Christmas special 'A Christmas Carol'.