In reply to Blackrainbow:
Last year myself and a friend camped at the Gwern Gof Uchaf campsite in Snowdon, did the Snowdon Horseshoe on day 1 and then got an early night and early wake up and did Tryfan and was down for about 10am and home for 3ish I think.
Then later we went to Side Farm campsite in the Lake district and did Striding Edge/ Helvellyn and the next day the coledale horseshoe.
Both were awesome and I plan to go back to both at some point and do different walks. I think 4-5 hours from London to both of those places.