Hi & Help!

I've been reading through lots of posts to gain some gems but I can't seem to answer this one...

I've just got a new FZ18 and have been advised to get a UV filter for it.... but the choice of single or double coated, UV or skylight.... its like trying to choose shoes.... 

Also does price/make matter - theres some on Ebay for 2.99 quid ranging up to the Panasonic one which is 32 quid.....I was thinking about a Kook one, but then saw B&W come highly recommended.

What is the difference?