In reply to spacecadetjake:
Take a look at Cadshaw Castle Rocks, between Bolton & Darwen. It's a trad crag, but has plenty of stakes to setup a top-rope. Natural coarse gritstone with a bit of polish. Loads of lines in the VD-S range.
You will probably need about 20m of static line and a handful of screwgates to comfortably rig everything if you want to belay from the ground.
This crag is pretty stable, but have a think about a helmet for at least the little people. They don't understand enough to make the choice themselves
Steve