Oh right, your cable UBR. You can work that out by looking at your Internet IP's hostname. If you're not sure how to find it, go to
Gemal.dk Browserspy then choose IP Information. Your hostname will contain a name that will help identify where it is.
For example, I'm on NTL and my hostname ends winn.cable.ntl.com meaning my UBR is in Winnersh.
When I had Blueyonder my hostname was something like chap.blueyonder.co.uk which is Chapel Hill in Bristol.
Not sure how to find out anything more specific than that for cable though.