Theres quite a few of us around Bristol. Spartan airsoft up near the airport is a very good site and both Cribbs Causeway and Portishead Black ops are good.
With the current weather though, Bristol airsoft in the old magistrates court may be a good bet. I unfortunately am a bit short of cash as I get ready for a 2 day D Day game near Bridgend, so won't be going to any normal skirmishes for a few weeks.
If you fancied trying WW2 airsoft, its a 2 day game and it may still be possible to hire weapons and uniform
http://www.ww2airsoft.org.uk/php/phpBB2/viewforum.php?f=266&sid=c1954ff77f045f5411e44e88b0600af0
It's not very often that airsofters get use of a beach for an amphibious landing