A couple of my ex GW colleagues run this club which isn't a million miles away from Dartford:
[url]https://sites.google.com/site/medwaywargamessociety/[/url]
It's a great club and a great bunch of guys and they play pretty much anything there.
Also there's Dark Sphere close to Waterloo. They have a pretty big gaming space but best to check before heading there as they run quite a few events. I know that's not as close as Blue water but pretty easy to get to on the train.
heard today from a very reliable source that there will be a new GW in Chavham.... sorry Chatham soon so looks like the hobby fix isn't lost for you just yet
Go to Rochester Games and Models, club night is Tuesdays.
Great independent store, haven't been down myself in a while but really nice group of guys.