This sounds like the exact opposite of what I want. One of the [many!] things that annoys the hell out of me about eBay is that --no matter how many times I tick the box that says 'UK Only' for 'Item Location' it always defaults back to 'Default' [which shows results from international eBay sites] on my next search.
May have found a bug thanks to your comment. Seems like the selected Item location is not being sent in the search query. Will check it out later on this week.
Just fyi and for anyone who might find this, The bug I mentioned in the previous comment is fixed, you can now select a location such as UK and it will only show listings which are in the selected location.