In reply to David Kirsfelds:
If you work just south of Blackburn, Boulder UK is the one to go to. Not massive, but the problems are always well set.
Rockover is probably the biggest bouldering wall in the area and only 30min from Bolton if the traffic is good. Best not to go during rush hour.
Plenty of outdoors options too. New Lancashire Bouldering guidebook out soon, so you won't run out of things to do!