For £400 you could get a 2nd hand Laney AOR head (more or less a JCM800 with more gain) and a cab and it'd eat ALL of the AVTs and Mode 4's you could throw at it :)
There's obviously other options aswell, but this is just a suggestion.
I dunno if it's still a valid option but a few years ago I got a 100w JCM800 2210 Split channel head for £220, and that amp easilly covers G n R and Velvet Revolver etc :)