If you hire and you go straight there at full speed then around 20-30 minutes (depending on the speed you choose). If you go with a tour then around 45-60mins. What are you thinking of doing?
Yeah you can! No need for any sort of special license whatsoever. We are also from the UK and have UK driving licenses and we were left on the boat alone. We did literally exactly what you are wanting to do. I also just checked and the minimum age is 18 so you're good to go!
Haha good question. They have a patrol boat along the coast and provide you with a radio tuned to its frequency if anything goes wrong. Neither of us have ever driven a boat before and we were nervous too but it was an absolute breeze 😄