Sounds like you need to SET PREFERENCES.
Go to MY ACCOUNT, --Preferences--Account settings. There you are given the option to specify what eBay site to list on. ~~Default eBay Listing Site
~~ Choose UNITED KINGDOM, then make sure you "Update"(save) at the bottom of that section.
Then, when you start a new listing: Make sure that the proper site is on the top of the listing page.