You can use adwords new keyword tool beta and insights for search tool to get a rough idea on search volumes.
Just an extra bit of info. for you:
In Google Webmaster Tools, you can choose a "Geographic target" for your website if it has a .com address, but for a .co.uk address this option is not available, and it just says "Your site's domain is currently associated with the target: United Kingdom" (i.e., you can't change it). So, as someone already said, it will be geographically targeted, and there's nothing you can do about it. See this page for more info.
You can also check: Location targeting Options
On a search for "john and edward grimes" from the UK star search, the uk sites are showing. So it is possible for the UK sites to appear in the regular results.
[ame=http://www.google.com/search?hl=en&source=hp&q=john+and+edward+grimes&rl z=1R2GGLL_enUS328&aq=1m&oq=edward+grimes&aqi=g1g-m9]john and edward grimes - Google Search[/ame]