If you go to Bizer's site, you should be able to download a sample. If you can see the sample, you should be able to download the map.
When I did that, I had to zoom in a lot to see the map.
If it is an auto GPS, realize you probably will not be able to set up routes, and there will be no bread crumb trail to follow back.
With my Street Pilot, I set my dock as a location, and when sitting in the middle of the broads, I selected my dock at Parkers as a location. When I hit "go", it said to drive to highlighted route (rte 11) and then turn left!
Did use the map with good success until I got my 76cx a year ago. Still use it and love the Bizer. Good luck.