Thorpe Island on the River Wensum in Norwich has a railway line running across it, so has a bridge either end of the backwater but the eastern end is only accessible by boat.
There is a lagoon on the western end of Thorpe Island which would be a fantastic location for floating homes and it is even has car access via a small bridge. It is home to several houseboats but I have not been there for a few years and so things might have changed. The island is also called Hart's Island and was home to a big fleet of Hearts Cruisers.
The Norfolk Broads are a fantastic place to enjoy the water but the Broads Authority are very strict and not at all keen on houseboats. This is probably because many of them do look like sheds on floats, therefore there are very few residential moorings available. Thorpe island in Norwich has a few but there is much dispute as to their legality. Brundall does have a few residential moorings as well.
Maybe the the Broads Authority should take a leaf out of Scottish Canal's plans to introduce floating homes all over Scotland. Eco friendly sustainable floating homes would fit in very well with the Norfolk Broads.