For those who are not aware there is a website called Jack's Flight Club https://jacksflightclub.com where you can receive details of cheap flights and special offers, these can be any destination and any airport within the UK (there's an EU site as well). A friend of mine recently flew London to LA for £200 return.
Some of the flights need to be fulfilled on a last minute basis but worth considering if you're not too constrained by your ability to leave at short notice. Some recent examples:
London to Tokyo at £269 return
Edinburgh direct to Iceland at £52 return
Manchester direct to Cuba at £330 return
London direct to Turkey at £59 return
Glasgow to Panama at £363 return
[Business Class] Manchester to Thailand at £606 return
Bristol to Venice at £32 return
London direct to New York City at £243 return
Liverpool to Morocco at £28 return
Sign up is free or there is a premium option to receive more deals and other special offers, currently £35 for a year.