In reply to unicycleboy:
I assume you have a car to get to the campsite?
Not really walking to the crag, but the pub near the slipstones is a mile or two away and it allows camping in the rear. I have no idea if it's open, but knowing publicans....
I think it's called the Swan.
Slipstones is a great crag, but best if you're in the low font 6s. I believe higher is fine too, but never made it that good when I was nearby.
Might be a rave at millstone or ilkely over Xmas? A little bit left field, but who actually needs sleep?