I think you wouldn't have any problem if you brought your own boat over here. What you may not be able to do is rent one locally. Although I am certain many British tourists and residents do, so I don't know. You don't have any sort of piece of paper that says you "can" handle a boat, at all? 

 Nothing, I mean, they're available but not essential, I think they actually let Darwin have his way in at least one area of our lives