Here's an update.
I logged into our CRT online account, maybe I'm super thick, but I couldn't see anywhere to update our moorings. So I gave CRT a call (it does irritate when the number is automatically answered with some blurb which you have to listen to, then you're told to hold for an assistant).
Got through to a very nice assistant, she confirmed they do need to know our whereabouts. She took my name and the boat's name and number, but she couldn't continue with my call as she needed to speak to the holder of the license, my OH.
Eventually, I found OH outside. The assistant wanted OH to confirm his name, date of birth, postal address, email address, and telephone number.... he stumbled a bit on the telephone number (senior moment), but she held out until he got it right. Obviously the correct name, dob, postal and email address wasn't enough to confirm who he was.
OH told her where and how long we're in the marina. She asked us to let CRT know when we venture out of the marina in the Spring.
She also asked OH if he would confirm that in future I'm authorised to speak to them on behalf of our boat!
Anyway... all's present and correct.
Thank you, everyone, for all your advice! Much appreciated