Nothing terribly interesting in the UK. Try France - but not the N coast necessarily. Try La Rochelle, etc.
about 1hr - 1:30hr flight time from Stapleford
If it's a 100kt plane, where can you get in France beyond the N coast? Not La Rochelle I assume - according to Google Earth that's 334nm as the crow (not necessarily the plane) flies from Stapleford. Or are we talking something a lot faster than a 172/Warrier?