A holiday on the Broads is most relaxing and is usually spent meandering along the river at a few miles per hour. The vast majority of people who hire a boat on the Broads have had no prior boating experience myself included. The boat yard staff will take you for a trial run and show you the ropes "excuse the pun". Most will find boat handling quite straight forward, especially if you have a crew. My wife helps with the mooring but I leave moorings normally unassisted. Any teething problems are normally comical and just part of the fun.
Regarding the above printable unofficial L Plates, feedback received confirmed that people did notice them and that help was regularly offered when mooring up. People sometimes hesitate to help as they are aware that some of the more seasoned sailors prefer to handle their boat unaided. The L Plates make it clear that help would be most welcome.
As already stated I am no expert and have had no specialist training but I have been taking regular boating holidays on The Norfolk Broads since 1970. I am simply passing on tips based on what I have picked up and from personal experience that I have found helpful to me over the years.