Actor, comedian, and writer Cornwell -- who will play Charlie --is best known for Stella Street, which he co-wrote and starred in with John Sessions. He was last on stage earlier this year in the world premiere of David Elridge's In Basildon.
Croker -- who will play Pauline -- came to prominence in 2008 with her comedy partner Stephanie Jory. She was last on stage in The Roman Bath at the Arcola Theatre.
The actors join current cast members Owain Arthur, Martin Barrass, David Benson, Nigel Betts, Derek Elroy, Daniel Ings, Ben Mansfield, Jodie Prenger, and Gemma Whelan. Gavin Spokes will also join ensemble members Robin Berry, Gillian Budd, Andrew Dennis, Laura Matthews, and Richard Shanks.