I always stay at the Radisson - easy walk - shuttle very reliable. Just an airport hotel, but you really don't need to be there that long. Take one of the later flights from LHR (LHR flounge time) and early flight back (the DAA lounge is quite pleasant) in the morning doesn't leave much time to 'enjoy' or not, as the case may be, the hotel.

Ive typically paid say 70 euros total. When its expensive (it has been a few times) use your club Carlson points as they have stayed the same amount when I have been there.