I stayed at Hampstead Heath in London for a week or so last month. Very nice place - quiet, clean. smallish rooms. The showers were clean (not immaculate, but clean) and hot water was plentiful. There's internet access right in the lobby, and you get free breakfast with every night - a full English breakfast, too, not a bowl of cold cereal. They have laundry facilities (use the dryer on the right!) and a full kitchen. In all, a really good deal for 20 quid a night.
Downsides - out in zone 3, so a little annoying to get to (not bad if you get a travelcard). Also, perhaps a bit too quiet for some people, not really a big social scene - although it may be different in high season. And there are plenty of fast food places down the road (including a great chip shop just on the other side of the tube station) but no good pubs in the immediate vicinity.
Still, can't beat it, I'll be back.
A ship in port is safe, but that's not what ships are built for. - Grace Hopper