if you can make scotland, there are guitar guitars in glasgow and edinburgh. i've been to the one in edinburgh and it's nice, sound-proof (at least i hope so :lol: ) testing booth etc.
it might stock the same stuff as the newcastle one, but i guess it'd be worth a phone call to see, just in case they have some different stuff.
amps you should look at in addition to the ones you've mentioned (that i can think of offhand):
bogner
brunetti (not too sure about dealers unfortunately, but the xlr-evo i tried was great)
cornford maybe (perhaps not enough gain/modern tonality)
EDIT: just checking the sounds great website... you might as well try the krank revolution and krankenstein (who knows, you might like them!) and the modular randall... might as well try laney too. and mesa. budda maybe? might be a bit like the cornford, but worth a try too.
ones i haven't tried but would were i near sounds great: cae od100, soldano slo (the avenger's nice),
you're after modern metal, right?
also, is the SE worth it? not sure. It kicks ass, but if you want the uber-saturated high gain engl tone, you can probably get that with a powerball (i haven't tried the two head to head though, it's possible the SE's tone is slightly better), and if you want more versatility, you could possibly get as much, if not more, by buying said powerball and then another amp for low to mid gain stuff. of course, you'd need space for two amps.
basically, i agree with what guitarist said in their review... there are amps which sound as good as the SE for a grand less, but none as versatile (which still sound as good) for a grand less. it really depends what you're after.