While on the ferry, it is likely that any of the crew can get you pointed in the right direction, driving permit and all. I have rented this way a few times.

The car has been in the lot across from the terminal exit and the key was handed over along with the driving permit while on the ferry.

They drive on the left, and the vehicles are sometimes US models so it can be confusing

"It is good to do nothing all day, and then to relax"