LONDON — Brit thesp Peter Serafinowicz has boarded the cast of Peter Billingsley’s “Couples Retreat,” alongside Jason Bateman, Jon Favreau and Vince Vaughn.Pic, which producer Scott Stuber has set at Universal, is about a couple on the verge of separating who convince their friends to go on holiday with them. Serafinowicz plays the British owner of the holiday resort the group journey to. Filming has begun in Bora Bora. Role is Serafinowicz’s most high-profile to date. He has previously starred in cult U.K. TV shows “Spaced,” “I’m Alan Partridge” and “Smack the Pony.” His self-titled BBC comedy skein “The Peter Serafinowicz Show” earned him a Golden Rose award for best entertainer earlier this year.