The power adaptor issue is insignificant - it's just a cheap £2 plug converter you need! The power supply itself is 100-240v and will work virtually anywhere in the world.
Second, Apple USA will not ship you a computer outside the US. Sorry. You could always buy one in Duty free in the airport though (after say a £150 holiday in Paris
, if you want to save the VAT.
If you look on the Apple Support Discussions site, you'll see people reporting that the iMac is whisper quiet - quieter than the Rev B edition. Plus, you want that damn remote; you can wake up and put your iMac to sleep with it
The mini really cannot compare with the new iMac; it's not in the same era of processor. The iMac at £899 (with VAT) is a GOOD deal; you'd be hard pressed to find a more elegant powerful machine in the Windows world.