Please beware of buyers who buy your UK-only items and pay the UK postage. Apparently, even if you only quote a UK postage (so buyers from abroad cannot get a price for non-UK countries from the listing page) once the sale has gone through, if you then notice the non UK address you can only request additional postage, but the buyer does not have to pay!
Please remember to specify in your listing that items are for sale only to UK (or whatever countries you ship to) and that buyer MUST pay the postage for that country.