Paintball is probably not as big as in the US but there is a firm following.
If you are into Speedball/tournament etc then I know little, but believe it to be popular.
In the woods you can either have:
the standard man off the street / punter / days, but if you are already a player then I don't recommend it. High pricing and newbies.
Many sites cater for walkons. I would try to avoid the newbie/walkon mix and find the dedicated walkon days (Usually monthly). Check out
www.walkonzone.com
check out
www.talkpaintball.com for one site which is also the home to a new series of woodland tournaments.
Finally you have the big games. Mainly Sunday one day events, but some cater for you to have minor games accross the weekend.