Hi PaulMycroft,
While you can always change the country code in the querystring, it's a backwoods way of doing things and I'm not convinced that one actually sees the results they're looking for. In looking for a solution, I came across a slick tool I'm sure you'll love.
Google Global Firefox Extension V2 is a FireFox plugin that adds an item to your context menu so you can see only the Google results from the country you specify.
Perform your Google search as usual, then right click to select "Search Google Global" from the context menu, then pick the country you want to see results for. Additionally, you can add/edit and delete countries as you see fit.
Detailed usage instructions are located on the download page.
Enjoy!