Completion should be this coming Friday and the new owner wants to go out on the Saturday, theoretically, he will be the new owner if everything goes as it should. Once I know completion has taken place, I will issue the change of particulars to CaRT. As far as they know I will be the owner so no problem in me buying the week licence.
If the boat was spotted on the river, I presume I would get a notification from CaRT but what else might they do?
If it's going to aggravation for me or the new owner I would sooner pay.