When you are completing the listing form, you mark as free Postage in the postage section then move to or use add another and enter postage for Europe, then if you want to add another enter Postage for Worldwide.
If no postage is entered any bidder/buyer from outside the UK, may still be able to buy BUT without postage cannot pay.
You do need to go through Countries or parts of the World you do not wish to post to, there are many places that it is better to block, War and Trouble spots for example..
