Yeah Stu, I have 2 TomTom plus in car Smartnav.
The problem at the port was that there was a queue of lorries filling the road waiting for crossings, probably at least a mile long. So signs were obscured, we weren't even sure we were heading in the right direction, and we had to do the whole piece on the wrong side of the road, with a caravan on the back so no scope for turning if we'd guessed wrong, or getting out of the way fo oncoming traffic. (And we'd absolutely hammered up to catch a ferry only to find it had gone 2 hours before...I shoulda read the documentation!!!)