Born in Ebbw Vale, Blaenau Gwent, March's career began in 1979 when she played Madge in several episodes of the series The Dick Francis Thriller: The Racing Game. Throughout the '80s she mainly did comedy. She appeared in episodes of Victoria Wood As Seen On TV (1985–1986), was regular Amanda in Life Without George and also appeared in The Upper Hand and Nelson's Column
During the 1990s March played a host of leading roles in numerous television dramas such as Close Relations, Goodbye Cruel World, Peak Practice, Seekers, The Bill, Inspector Morse, Oliver Twist and Wilderness. She also was a regular leading soap character, Liz Kemp, in the series London Bridge, spanning nearly two years.
From 2000 onwards March featured in many more British television series and TV films like Top Buzzer, Men Only, Swallow, Poirot, The Second Coming, Holby City, Doctors, Nicholas Nickleby, Heartbeat, Rosemary and Thyme, Class of '76, Ahead of the Class, Zip and Hollow, New Tricks and Eternal Law. She has also starred in several major films: East Is East in 1999, Calendar Girls in 2003 and Flawless in 2007.
Stage work includes, Dear Daddy the Ambassadors Theatre, Olivier award for best play,Ooh La La, Hull Truck at the Bush, Mill Fire at the Bush, View From the Bridge, York Theatre Royal, tours of Rebecca and The Real Thing, Suspension, at the Bristol Old Vic.
In 2015 March appeared as Liz Grey in the ITV series Midsomer Murders episode 17.3 "The Ballad of Midsomer County"