Bunker 51 has a captive audience in a very large heavily populated catchment area, & is supported by an immense public transport system.........you could literally run games there at midnight & people would have no problems attending, I doubt the same could be said of ANY towns in Kent, personally I wouldn't travel for an hour or more for just four hours of gameplay at £30, no matter how short your briefing or how fast the turnaround between games.
I realise your overheads so far have been astronomical, but your not going to recoup them with your only real selling point being "it's cqb innit".
IMHO, maybe it's just me ?