How do I set my default search engine to google.co.uk when using Safari's address bar?

How do I set my default search engine to google.co.uk when using Safari's address bar?

The only option offered in Safari's 'Search' preferences is for 'Google' generally. This means when I perform a search in the address bar it takes me to results from the .com site which means I get results from America as well as everywhere else. This is no good for me generally, especially when I am at work. Trying to order architectural products from a completely different country is not very cost effective! I know if you search from the local google website (i.e. google.co.uk) it is possible to filter results by location. This is why I would like to able to set my local google.co.uk website as the default browser search engine rather than traveling to google.co.uk every time I want to perform a search.

Thanks for your help

Tim