So we did roughly this walk:
http://www.trekkingbritain.com/blackmountainfromglyntawe.htmland camped next to the lake Llyn Y Fan Fawr which is a good spot - found a nice flat grassy patch. Spectacular views and handy for water. Oddly another couple of backpackers turned up and pitched their tent about 40 yards from ours, on a slope. No idea why they wanted to be that close given the huge area and choice of potential pitches there.
Weather was amazing on the Sat - clear, bright and cold. Wandered around the sink holes and up a couple of little peaks, had a spot of lunch and over to the main escarpment - amazing views and strong winds.
Then got confused as to the path down the side, confusing a stream with a little waterfall with the actual path which made for a more exciting descent that was required! Then over to our camping spot at Llyn Y Fan Fawr[/size]
Night was flipping brass monkeys - dropped to -5C under a clear sky but not one for sitting out star gazing despite wearing every jot of clothing including down jackets etc. Didn't even have the will to wash up but rather got into sleeping bags ASAP. But we battled through courtesy of a bottle of rum, lying on our backs in sleeping bags yakking. The next day was decent weather too and a short, easy walk back to the car was very welcome.
So a nice jaunt not too taxing which was ideal given my current fitness levels.