I agree that it depends on the branch and when it's good, it's really good. Had a cracking lunch in the Guildford one.
I woudn't go back to the Bluewater one. We were lured in by the 2 courses for £12 offer written on a huge board outside. The place was virtually empty. The waiter gave us the normal menu and I got a sigh when I asked for the offer menu. Sorry but if you want people ordering a la carte then don't put an offer board outside!
I'm sure you'll enjoy it in any case - food tastes better when it's free.