Hmmm...I don't know of any communities but I have just bought my first 10mm minis, which my bro and I plan to use to play Warmaster and also Warhammer with. The problem isn't finding basic minis (like Infantry & Cavalry) but rather the more exotic artillery and some of the special minis like the Screaming Bell etc and also Daemon substitutes seem impossible to find.
I heartily recommend Pendraken for their Fantasy and Medieval range and also Kallistra (who's Fantasy Range is based off Pendraken's with a few extra sculpts and put onto strips rather than individual minis).
http://www.pendraken.co.uk/Fantasy-c21/
Pendraken don't have too many pics up but a Google image search usually brings up something and the minis are better than they appear. Their Medieval and Renaissance ranges are also worth checking out for Empire-type minis. I can say that the Pendraken minis scale up nicely to Warmaster's, although the cavalry is a touch on the small side in a one-on-one comparison, but infantry seem fine.
http://www.kallistra.co.uk/?page=19
Kallistra's other minis are more big 10/12mm scale but apparantly fit well with Pendraken's Fantasy range. They also do some nice looking Hex terrain and their rules seem quite good too.
http://www.copplestonecastings.co.uk/range.php?range=FAN
Copplestone do some nice
LOTR style minis.
http://www.magistermilitum.com/prodtype.asp?PT_ID=1209&strPageHistory=cat
They have some nice Elves.
If you're looking for Terrain then Total Battle Miniatures do some great looking 10mm stuff, including roads & rivers:
http://www.totalbattleminiatures.com/bigbattalions/10-15mm/blackpowdereurope.html
I also recommend buying an Ultrasonic Cleaner to help prep the minis (as it's hard to clean 6-15mm minis) you can get them from £20-40 and they clean minis even plastic/resin ones) like no scrubbing ever could.
Hope this helps