Hi Easyjet have a one way flight for £129 including taxes from Gatwick to Sharm 3rd and 10th June. But you need to be quick or it will be gone or the price will increase.
See
easyJet.com - book cheap flights, hotels and car hire online
Thomsonfly have a flight 1st June from Gat to Sharm for £134.99 incl taxes
see
http://www.thomsonfly.com/SelectFlight.aspx
I cant find anything cheaper at the moment from Manchester.