Try driving in B3's - mega sketchy!
Dave, how far away from Dartmoor are you? Dartmoor is a bit of a mini bouldering mecca, so if you can get there you'd love it! Have a look at UKclimbing.com - Theres quite a lot of info there, you can search for local centres too. Beware of the forums though, it has its trolls like every other...
With regards to shoe differences you're paying more for rubber type (soft and sticky vs hard and stiff (giggedy) ), outer contstruction, reinforcement areas (heel cusps and toe boxes) and other constructino methods that promote performance in certain areas. REALLY, if you're just starting, don't bother with expensive stuff, because a pair of toe-hooking wonders like the la sportiva solutions would be useless to you if you can't toe hook!
Get to your local bouldering wall and just crack on. Speak to people (climbers are usually friendly) get advice and beta, learn technique, get stronger, crush, win world championships....etc.etc