Page was born in Treboeth Swansea, Wales, the only child of Susan Angela (nee Foster) and Nigel Leslie Page. She attended Mynyddbach Comprehensive School where she was head girl. She graduated from the Royal Academy of Dramatic Art (RADA) in 1998.

She married British actor James Thornton in December 2003.

Page has appeared in From Hell, Mine All Mine, Love Actually and Miss Julie and in several productions at the Royal National Theatre and at other theatres. She starred as Mark Owen's love interest in his music video for "Makin' Out".

Page stared in the BBC Three comedy Gavin & Stacey, playing the title role of Stacey. On 23 November 2007 she turned on the Christmas lights in Barry , the town where Gavin & Stacey is partly set and filmed. She also had a leading role in the 2001 BBC Production of The Cazalets, about a disparate well to do English family during the Second World War.

In 2009 Page provided the voice-overs for a series of Kingsmill bread TV & Radio advertisements and the Christmas TV advertising campaign for the Carphone Warehouse.

During Christmas 2009, Page played the role of Cinderella in pantomime in Woking, a role she played a year earlier in Wimbledon. She will be appearing in Dick Whittington at Milton Kenyes this year.

Page was nominated for Best Female Comedy Newcomer at the 2007 British Comedy Awards.