Punk is not dead in the UK, it's still very alive!!!
If you want to retrace your routes to Glasgow there's a good music scene with plenty of Punk gigs happening at The Garage and The Cathouse, check out http://www.cplweb.com/ for gig info.
London will always have a punk scene, Camden is full of real punks (as well as the posers and kids etc etc) Shop around and you'll find some good clothes and records (as well as a bunch of crap too if I'm honest)
I live in Manchester, there's a good punk community here. My punk friends often talk about a vibrant community called "mancpunkscene" but i'm having dificulty finding there website right now, sorry!
There's a website called metaltravelguide.com which although it specialises in metal places around the globe, it often features other rock stuff including punk.
Basically, don't let the other ignorant "answers" put you off coming to this country. You will find fellow-punks in most cities, but you will also find ignorant fools too (probably much like wherever you live right now and the rest of the world)
Good luck!