In reply to Cake:
They're two different sites, but right next door to each other.
The bar (The Paddler's Return) is at one end of the Anglesey Outdoors site, and there's a pedestrian gate from there through onto the Valley of the Rocks site. I don't know about the camp site never being full, but the bar often is! V friendly place though, and the food is remarkably good.
Anglesey Outdoors also has a pretty fierce drying room, which could be handy.