Born in 1980, to Wendy and Richard Mantin in Norwich, Mantin attended Norwich High School for Girls.
Mantin started her media career at the Norwich and Norfolk commercial radio station Broadland 102. She then transferred to television with Anglia Television, firstly solely as a weather presenter, and then reporting and presenting regional programmes including the short-lived consumer show Late Night Checkout.
Mantin then started to appear on the ITV National Weather, Channel 5, Sky and on ITV’s This Morning as an occasional reporter. From 25 February 2005 she ceased duties with ITV Anglia, and permanently transferred to the ITV National Weather team, working alongside Martyn Davies and Siân Lloyd.
Mantin married London Irish community rugby coach Jack Heald on 12 December 2009.
A keen surfer, Mantin was struck in the head in a surfing accident on 7 June 2007 in Cornwall. She was pulled out of the water and initially rushed to hospital with concussion and slight memory loss. While at her parents home in Norwich a week later, she collapsed and was rushed to hospital for a brain scan
Mantin returned to ITV screens on 23 August 2007, however she was still experiencing dizzy spells and was signed off work again only to return to full time presenting early in 2008.
Mantin announced on ITV programme This Morning on 13 April 2010 that she was 14 weeks pregnant with her first child. She started her maternity leave in September 2010.
Mantin returned to work as a weather presenter on ITV on 08 March 2011 following her maternity leave. She had a boy named Rory, born October 2010.