Outside Doctor Who, she is likely best known as one of the stars of the long-running programme Two Pints and a Packet of Crisps alongside Kathryn Drysdale. She also starred with Paul McGann in the 2010 Jonathan Creek Easter special, "The Judas Tree".
Smith is a double Laurence Olivier Award winner. Her first Olivier was for her work as the first British Elle Woods in the original West End run of Legally Blonde, co-starring Peter Davison. Her second came from the 2011 West End revival of Flare Path, which also starred James Purefoy, Sarah Crowden, and Clive Wood. In 2013, she picked up a BAFTA for her performance in Mrs Biggs, a production in which she starred opposite Daniel Mays.