Hi, and welcome to TB. Regrettably I have no advice about the GT10B, other than if this thread doesn't get you the response you need, you might try posting a thread with a title like "Boss GT10B owners please help". That way you are more likely to get an answer from someone who knows.
As far as the amp questions, here's the drill: The Amps forum is the place to look.

When you ask over there, you should specify the following:
-Your real budget, a specific maximum amount. Don't just say "affordable" or "won't break the bank" or something like that, because everyone has a different idea of what those phrases could mean.
-The types of tones you want (exactly as you did, with Trujillo/Infectious etc.).
-Remind them that you're in the UK, as that may affect your options.
-Whether you're willing to shop around on the used market, or if you need to go through a new-goods store or website.
Do all of that, and you should get some actually helpful input. Good luck!