last time i was in the wembley guitar centre (also known as the only time I was there, and this was about a year ago) they had engl, peavey, laney, marshall, mesa, fender, and ashdown (not the FA, though, although they may have that now). I see they've since got in H&K, so you could try those too.
I'd head there as a first stop- they had the screamer and laney tt (head), but of course they could have sold it by now...
also, machinehead. They stock the screamer and rivera, and other guys like the vht pittbull combos that might be worth a look (about a grand, though) so if you get to try the screamer in the WGC, you can judge the riveras and the others versus that.
It's very rare that you get to try everything you want to in the same shop. So what I do is to try to try one amp that I can try in more than one shop, and kind of use it as a measuring stick... e.g. when i tried the screamer versus the tsl, the screamer was better, then another shop maybe has the tsl which you can compare to say rivera, and finally a third shop has h&k which maybe has a screamer to compare to. You know what I mean. I just know that unless something is really terrible, I normally end up liking it, unless I have something meaningful to compare to...
and of course it depends how much you're willing to spend. You'd be hard pushed to get better than a screamer for £800 (assuming you need a large range of tones), but if you're willing to stretch to £1000 or £1200 you should be able to get as good, at least. And if you aren't even willing to go to the screamer's price, then you have to decide again...
Hard decisions, man. And nomatter how much research you do, something will happen after you buy that you didn't know about...
:drink:
