It would appear from the Google Labs that Google SMS (UK) has graduated from the labs. It used to work. But doesn’t any more!

All you get now is a message which says
“Google SMS is currently not available in the UK. The service is still in beta, and we’re working hard to make it better.

For more information about our mobile services, please see mobile.google.co.uk.”

Then you get redirected to the Google Mobile page. Google mobile is not as good, for many things.