if you are in London, there are not many shops that have too many really high end guitars other than Soho Sound house and Sound Control, both of which stock several PRS's but thats about it (apart from the Gibsons and Fenders you find in every guitar store there). Try Vintage and rare on Denmark Street (near Soho Soundhouse and Soundcontrol...Tottenham Court Road tube station.) They stock some really nice vintage axes, as do Wunjo guitars, which is just around the corner...

If you head out to Leytonstone (east London, zone 3 on the Eastbound Central line) you can go to Holliday music, that stocks a fair amount of Nik Huber guitars, as well, as some nice amps...Koch!

also, on the extreme west side of the city, you can find Peter Cooks guitar store in Hanwell, on station Road.

other than that, you have top head out of London...there is a place up in Ashbourne Derbyshire, which I strongly recommend...It is where I bought my Prs...its called Guitars4you look at wwww.guitars4you.com to see their stock..it might be .co.uk come to think about it.

There is also Machinehead which is in Hertfordshire, and a few others around...Wembley Guitar centre in NOrth London also stocks some nice high end guitars...

Sounds Great near Manchester stocks some Suhr, Anderson, Prs, and James Tylers that are very nice, they also get Terru Mcinturffs, and those are amazing.

Otherwise, look at www.exoticguitars.com (again, might be .co.uk) this guy sells alot of Prs, Anderson etc guitars...and is a great guy too.

Engalnd is also full of great custom shops...
Nathan Sheappard guitars is based in Somerset and has some amazing stuff www.nathansheappardguitars.com

Black Machine guitars, based in North London has some really killer guitars, including a new 8string, fan fretted model that looks like it is beautiful to play...www.blackmachine.net

also companys such as Pendells, and Organic guitars are English made and very nice.

When it comes to Englsih custom shops tho, you cant mention a list without including Patrick Eggle guitars, in Birmingham, or Hugh Manson guitars in Exeter...both are world reknowned luthiers...both make awesome guitars.

Moose, where are you originally from?