River and sea safety Direct.gov.uk click here
also click here
"The rules of the water are not as restrictive as those of the road. Unlike in a car, there is no current rule whereby a boater must first pass the equivalent to a driving test to demonstrate their competency in a boat. In boating a greater emphasis is placed on the competency of the boat itself. "
"Boating around the coast or further out to sea is open to all and does not require a licence. Passage down one of Britain’s many inland waterways however requires a boating licence or registration with the appropriate authority in charge of it."