Well I have a crappy 50 watt amp I bought off ebay and it works fine, if not perfectly on overdrive, but recently on the clean channel it's fine for about a minute but then the sound just slowly dies down to nothing and comes back again in a minute or so... It's quite strange... Is it that it's just a ****ty amp that I couldn't have expected to last longer than a year? Or is there something else? Any help?

How old is the amp?
Likely due to the no namedness of it that is a **** amp
Have you opened up the back and checked to electronics?
Yeah I opened the back.. It's all fine there. It's roughly a year and a half old and it does have a name!.... "Max Turbo" lol.....

Not that it's overly important since I plan on getting a decent amp once I get the funds, but I'd like to have something to play in the mean time.
I suppose if the sound is coming back and not completely cutting out then your amp isnt that dud. Atleast you've got sound!