In the play, Lisa and Ed are having another baby. Determined to do things differently this time, it's proving a bumpy ride.
Dillon's recent stage credits include The Taming of the Shrew and Knot of the Heart, and she is perhaps best known for her role as Miss Mary Smith in the BBC TV series Cranford.
Mangan received a Tony nomination and Drama Desk Award for his work in The Norman Conquests. He last appeared at the Royal Court in The People Are Friendly.
The production will be designed by Mark Thompson, with lighting by Hugh Vanstone and sound by John Leonard.