Thank you all for your contributions - some great advice; all noted!
I should say that I play in a 4 piece pop/rock/swing band, with lots of vocals i.e harmonies, plenty of guitars and, of course, a thundering rhythm section! So, we're not too loud.
The two cameras idea seems like a good one, and then going on to sync the sound afterwards.
There are venues in London which will film a gig for you, and I guess that option is to be used when appropriate.
The camera my band, The Hops, needs is more to document each gig and if anything is of good enough quality, to put on show at myspace, youtube etc.
Thanks again for the advice, I'm quite chuffed.
Regarding Route 66. In the late 80s it was THE place in Hanley, Stoke on Trent to drool over guitars. This is the place I bought a Capri Orange 77 P-bass for £270, and 78 Stingray for £695. It was run by Don and Karen. Don ALWAYS wore those big glasses with the bottom half shaded bit, and Karen was a bit of a rock chick..., or was. Lovely people who must've seen me at least monthly as I could not go to Hanley (from Congleton) without walking up the hill to, well, just go and look. Oh, they had a sale every year and I swear once they had a Dan Armstrong(?) plexiglass bass for "£85 or make us an offer"!!