i know a couple of people who have done just the same, the first person i knew who did it the boat was lovely but hardly a year round home and as jayday said unless you pay for a permanent mooring you have to keep moving to avoid the tax.
the boat wasnt really geared up for winter living ie centralheating and double glazing, and what i can remember he lasted one year before he went back to his parents, and sold the boat.
the other people i know bought a boat last year and it was mod con city in it very spacious two double bedrooms a seperate kitchen with dishwasher etc , a seperate dining room and a 40 ft lounge the boat was central heated and double glazed and pure luxury.
they have just sold their house in westbury and have just upgraded their boat which looks fantasic and something i would be more than happy to live on , they havent got a permanent mooring but travel to work each day in the boat and dock up in a different location each day.
ok if you have got the money to live in this way but personally i prefer a house
