It would be interesting to know the dates that you're trying to book for, what flexibility you've got around those dates, which outbound airports you can use and where you'd like to go to. (It would also be interesting to hear your definition of 'cheap'!).
I've just tried a few random dates and destinations and I don't seem to have had much difficulty finding (what I'd call) cheap fares. For example:
Stansted to Girona (for the Costa Brava): £45.99 out on Wed 8 June, £32.99 back a week later. (Ryanair).
Stansted to Malaga: Dates as above, £39.99 out, £54.99 back. (Ryanair).
Stansted to Palma, Majorca: £35.49 out on Sat 11 Jun, £44.49 back a week later. (easyJet).
Manchester to Alicante: £57.49 out on Wed 15 June, £65.48 back a week later.