http://www.tartybikes.co.uk/category.php?id=16 have a look at the freewheels on this link... i think you should get try-all freewheel because they have 108 engagements and 9 pawls. they are £50 but well worth it .
i live in Jersey and pretty much gets bought from tarty bikes, there are no bike shops which sell trials parts over here and some people occasionaly use chain reaction cycles
I think that you should get a pair of heatsink snowys and not get a rim grind. this will make your wheel last longer and you will have a perfect bite. Hub wise, you should sell everything you own (apart from your bike) and buy a king BMX hub!!