Ricky -
The engraving doofer on EBay is adequate for marking metal, it isn't really useful for what's generally referred to here. You could possibly use it for background removal, but that's about it.
There are a few gravers on EBay UK - both new and used. One listing on at the moment is number 250457521780; I've no idea what the profiles there are.
The bare minimum I'd suggest is a 2.5mm square and a handle; these are readily available from Sutton Tools, Cooksons or the like. You'll need an oilstone or something else suitable for sharpening - NOT one of the pound shop ones, something like a Norton, preferably one of their finer grits.
There's a lot of info in the thread "Inexpensive way to give it a try"
http://www.engravingforum.com/showthread.php?t=4 - pretty much covers everything you need. I can help point you in the direction of UK suppliers if you need.
Added - the most useful bit of advice I can think of off the top of my head: Keep your fingers out of the way!!!