Wow that tamron does pretty well. 3200, I'm only ever that brave when I'm drunk.
As for access in uk. Your asking the wrong person. I've never shot anything bigger than pubs and very small clubs, where they are desperate for the exposure and nearly drag you in to take phots. All I do for these is find a band I like check out the listing, ring the promotion company, promise them a copy of any thing worth while and I've not had a no yet.
As for the bigger stuff, I'm afraid I just don't know. I'm new to all this. Not sure if I'd ever want to do bigger stuff at all, you lose the intamacy that I really enjoy when the lead singer goes walk about and you can get shots of band and public at the same level.
Good luck when you come over anyway.
...it's arrived and it's in English...