sorry, they've changed how you do it
Specifying where you'll post to
You can exclude certain regions or countries from the places you're willing to post to.
To exclude certain locations:
Click My eBay at the top of most eBay pages. You may need to sign in.
Place your pointer over the Account tab and click Site Preferences.
Click Show to see the Postage and packaging preferences section.
Click Edit next to the Exclude postage locations from your listings option.
On the next page, select regions and countries where you don't want to post your items. If you only want to select certain countries in a continent, click Show all countries link next to that continent's name.
If you want to apply these exclusions to your current listings, select the Apply to all current live listings option.
Once you're finished, click the Apply button.
http://pages.ebay.co.uk/help/pay/ship-internationally.html?fb=true#where