I might consider it this year, don't put down for definite, but I
might see if I can make one this year. I strongly emphasise the '
might'. If not, 2010. This Summer I have 2 holidays as it is - a trip to the Wacken Music Festival in Germany and a holiday in Barcelona. A weekend out might be too heavy on my budget.
I have 2 homes (as I am studying at University): East Anglia (Cambridgeshire) and The Midlands.
The Lake District might work, or maybe the Peak district? I have a couple of friends of friends who know some good spots around there. Assuming everybody is fit enough to go around the peak district.

If you didn't want anywhere rural or out in the open (after all, we're meant to be geeks and we wouldn't feel at home with the outdoors)
For locations: somewhere central, in the Midlands, Manchester, as said, is a good spot. I'd make sure people's safety is taken into consideration, you wouldn't want people stepping into the wrong side of town alone later in the evening.
[edit]
Oxford is probably a nice place to go. A couple of good places I've been camping that are good for their rural locations are the Cotswolds and Sussex. If you're going to Sussex, avoid the campsite at Camber Sands...it is truly awful.