In reply to sjc:
Caley is very good for slabby bouldering - it's probably the best bouldering in the UK in fact and has loads to go at. OK it's a bit far from the Lancs border but I think you're being a bit picky there, either climb the decent stuff in Yorkshire, or don't. For slabs around 6a, the classics are Otley Wall and Low Pebble Wall. They're both high enough to give a little bit of a buzz, but perfectly fine to fall off. Another corker is Chicken Scoop, then there's Mr Smooth. There's also a good easy slab (might be 5c direct) which I can't remember the name of, but it's obvious and you could spend half an hour doing eliminates on it.
The list of slabby problems at that grades at Caley is really pretty long. Get a guidebook and go there. The only problems with Caley are that it's a bit dirty (litter, turds etc) and the Roadside area is, yes, right by the side of a busy road. It's also entirely useless in summer and very cold and rather damp in winter (but surprisingly often still climbable).
In the Peak, Robin Hood Stride and Cratcliff top boulders has lots of good slaby problems at that grade too, a great venue. And of course Burbage South - it's pretty boring, but there are tons of short, unscary 5c slabs all over the place, no need to fixate on particular problems.
