Born in London, she started out as an assistant for a London television network. Before getting her major break on television, she worked as an ad model, a voice-over artist and floor manager for the British gambling channel Avago and as an actress in NTL commercials.
Her most famous roles are of those as game show hosts (or presenters in England). Her first job as a presenter was for Spin 2 Win on Avago in April 2004. She left Avago in 2005 to be the presenter for Quiznation and other shows for the Optimistic Network.
In April 2006, she left Quiznation to work her first job in the United States came as host of GSN's PlayMania, a show with a similar format to Quiznation. She shared hosting duties with Shandi Finnessey, and later Jessica York, until PlayMania broke off into two separate shows in February 2007. She switched on and off, hosting the two programs 100 Winners and quiznation (The United Kingdom program's United States namesake).
The 7 April 2007 episode of quiznation was Peachey's "goodbye show" and her last night as host, as she announced a week earlier that she was to return home to London.  She began hosting Quiznation and Pop the Q again in the United Kingdom on 23 April 2007. However, the programs were cancelled by their respective networks by June 2007. She was a temporary presenter for ITV Play's Make Your Play, appearing in late June 2007.
Peachey was a presenter on the show Red Hot Roulette / Pitch Roulette, from 10 September 2007 until May 2008, when the show ceased using live presenters. This information is based on reports from various quiz-based message boards.
Mel has had other television duties, such as being a woman-on-the-street interviewer for a celebrity gossip channel or the co-host of a music video show . She appeared in the 2005 independent film Thoughtful Geezer and had a walk-by role in the James Bond movie Tomorrow Never Dies.