While Google Nav has been available in the US for months now, its launch in Europe has been delayed substantially. Legal problems between Google and Tele Atlas are credited for the slow-down. Whatever the issue was, it's been dealt with in the UK. GSM Arena reports that, as of last night, all UK Android devices have Google Maps Navigation.
If you don't see the update installed, just download Maps Navigation 4.1.1 Beta and get to navigating. Hopefully this update will spread to the rest of Europe in short order. Who wants to pay for turn-by-turn navigation?