After a last minute and highly successful trip to the Lleyn with the missus last weekend I thought I'd flag
Air BnB up as an accommodation option.*
There are numerous options for you from staying in a spare room in someone's house from £6 to renting a whole gite in Font for 12 of your cronies. You can do everything directly with the owner through the website. The owners get to check you out and decide whether to accept your booking or no. It's free to join and we were very happy with the ease of booking (once we were registered - which was a bit of a pain in the arse to be honest) and the place we stayed in. We also really liked the reviews feature. You can review places you stay at and owners can review you too thus you can build up a good portfolio and be more likely to be accepted in the future...
We were so happy in fact that we are looking to book a place in Fontainebleau in March through them as well.
*We are in no way sponsored by AirBnB, just happy punters