I don't think that amp was the best thing to use for comparison purposes. Tesco sells them!. If your Epi sounds good that's all you need to think about. From what I've read Epis can vary a lot in quality but if you're lucky some of them are really good.
Actually there rare as hens teeth those amps lol,look em up ;)
I just looked them up... Even maplin sell them :/
TS, if you we're lucky enough to get a good epiphone that's awesome for you, couldn't be happier, but playing through that amp is not gonna help for a proper comparison, and sound isn't the only thing to it, especially when plugged in because it is the easiest variable to change.
You also got to take into account build quality, playability, sustain and the unplugged sound and resonation.
All I'm saying is, if your epiphone is good for you - no worries, be happy, it could be excellent - but most of the time the Gibson will be better.