In reply to estivoautumnal:
My girlfriend and I live on a 57' narrow boat. I'd say it's something that you have to want to do. It's very small compared to most places I've lived so you never really have your own space. It can be hard to fix things that go wrong (unless you're handy) and it gets much colder than houses. Be prepared to get rid of most of your belongings too!
If you've got a mooring with electricity then that makes it more pleasant but without it you'll need lots of solar power if you don't want to run your engine for 3 hours each day (this isn't pleasant) for electricity and hot water.
Regarding the marinas, often you need to take out a longer contract (ours is 12 months but new ones require a 3 year commitment where I am) and are often quite hard to find. In Leeds, for example, there are only about 15 moorings which are permanent (more outside the city) and if you don't manage to get one it'll be a case of moving every 2 weeks, and that means a reasonable (mile or two at least) distance which then impacts commutes.
On top of that you have the whole toilet and water thing which can be a pain.
The whole thing can be pretty crap at times but we made the choice for 3 reasons:
1) We liked the idea and had spent a lot of time thinking about how we would make it work.
2) It means we can live in the city centre in the winter and move to the countryside in the spring/summer.
3) As we're not sure where we want to base ourselves it's a shorter term commitment than a house (we will own it in 3 years) and can treat it as a savings fund for an eventual house rather than paying rent.
My address is my parents but many people use other family or friends.
