I've bought quite a few odds and sods from various people and companies in various countries (AmigaKit included, and have always got good service there).
Generally speaking, most of the world (aside from the USA) is 220-240V, with equipment from the last couple of decades designed to work within those voltage ranges. Certainly equipment from western Europe would be fine, just requiring a simple mechanical plug adaptor (or just snip off the plug and stick a UK one on it).
As far as the OS goes, the Kickstart ROMs are (as far as I know) all in English with no regional variations. The language shown in Workbench will depend on software controlled locales, so that can be easily changed (or the OS reinstalled).
With buying stuff, if it's from a reputable company, I'll often use a credit card - this has an advantage of little or no fees to transfer money internationally, and sometimes the card provider will give you online fraud protection of some sort. It's certainly easier than paying rip-off charges from the banks. Paypal is another option if the seller/company supports it.
- Ali
