Most of time, Google employee like matt cutts and John Muller said, use Different country level domain like example.com or example.co.uk or example.de when possible, and secondly option is sub-domain(like uk.example.com) and third option is sub directory(like example.com/uk/).
The main reason it that, Because Search engine spider understand it, you want to target this location, so most of time, they will display country related domain in search result.
If you search Google analytics from India, then you will get www.google.co.in/analytics in search result. If you search from UK, then you will get .co.uk result. But the page is same, it is even in same lanagage, but they just target to different location, which you can set in Google Webmaster Tools.
Similarly, Godaddy also provide same service on different location, but their price value is different, and hence Google is smart enough to don't consider as duplicate webpages.
So, just create .co.uk domain for your website, change product currency from Dollar to Pound(I think they use pound), so Google understand this is not duplicate pages, also set target location in Google Webmaster Tools.
Please do not redirect .co.uk domain to .com site, it does not help in SEO anyway. Just like User redirect, Googlebot will do the same.