Sigourney Weaver and Celia Imrie are among the latest stars to join the cast, with Weaver playing Evelyn Wallis and Imrie cast as Francine.
The series, created by Phoebe Waller-Bridge, also features Jason Isaacs as Lara's uncle, Atlas DeMornay, alongside Martin Bobb-Semple and Bill Paterson.
Further cast additions include Paterson Joseph, Jack Bannon, Sasha Luss, Juliette Motamed, John Heffernan, and August Wittgenstein.
Jonathan Van Tulleken is set to direct and executive-produce the series, with production scheduled to commence later this month.