Hey Rusky, welcome to the board and great question.
A check on the "What's New" link at the top of yahoo.com and uk.yahoo.com give the same exact entries in the same categories. Also, the regional / UK section of the dot com seems to match the UK Yahoo exactly. By looking at that, I would say that UK sites get added to the .com. Anyone have an experience where submitting to the UK version did not get you in yahoo.com?
I'd second JamesR. Check out the database at Yahoo.com where you can drill down to the relevant geographical areas. By searching on Yahoo.co.uk you'll get filtered results (unless you select otherwise) for uk only.