I'll yield to Guest on this one.

My search for "Micro ATX" + anywhere in or near the UK - shows a lot of cases (from about 12£ (Moretec) on up to 190£ (the top at RipNet-UK), but I was unable to find anyone that lists power supplies separate from the case.

I suspect that the "right" dealer might have them, but they're a pretty low priced item to list(?).

I was about to suggest getting a cheap case - and considering the option of:
1. Put your machine in the new case, or
2. Rip the power supply out to use in your machine - and throw the case away (or maybe put it on ebay?)

Good luck hunting -

John