ok, heard you the first two times!campaign in cobham surrey is a great site with good facilities and maps they did time wars last year and the site looked great with good organisation and great fields like the sioux city.
But holmbush has a great woodland game base and its for walkon players only not great facilities infact basic but they are all ours so no sharing with punters and you have to love that.
As for best in uk that's a bit challenging as i have not been to all the walkons in uk.
but warrenwood is good
dragons lair good
dorking (surrey paintball)good
i would recomend all of these as good sites to visit.