Geo-targetting & specific results

Need to ensure UK results for UK traffic on a site using geo-targetting

[TinkyWinky]

Having done a little research, the following seem to be the two main IP ranges for googlebot...

216.239.38.*

216.239.36.*

Are there any others?

The reason I ask is that I have to put geo-targetting in place on a UK site that serves up PPC results to prevent US originating traffic from clicking on UK advertisers

This is fine, however when googlebot goes through to capture page info, from an SEO point of view these pages will show US advertisers amongst UK directory results.

I also run a US version of the site, and am showing US PPC on this site, which means both sites are showing the US PPC results...

So all I need to know is which US Googlebot IP ranges to 'act' as UK traffic on the UK site.

Any help much appreciated.

TW