Is it country, or language, that you are concerned about? If the latter, check out the article here:
http://www.phpbuilder.com/columns/didimo20010214.php3
If the former, you have a bit more thinking about what it is that altavista et al are doing. Just for starters, what if you did want to visit the non-uk version? If they're automatically transporting you somewhere else, how do you get them to stop?
As far as using the IP, that's pretty iffy. To see why, just go to ARIN.NET and pick any old random class-B size block and see what a crazy quilt of countries showed up. I just did this now for 192.100, and I got sucessive registrants from ZA, KR, US, FR, AT, AU, GB, NZ, US, GB, NO, US.