Peacocke knew he wanted to be an actor from the age of 16. He had many performances on stage at Newcastle University, one of which he was awarded a City of Newcastle Drama Award for his portrayal of Ricko in Nick Enright's A Property of the Clan in 2004. He went on to act in the short play festival Brand Spanking New with actress Bel Deliá in playwright/director Augusta Supple's work Interrupting Grace directed by Nick Curnow, and also on Supple's later venture Stories from the 428. He also had a role in Kit Brookman's It Was Raining All Afternoon.