Everyone has painted a rosy picture so far, but a few things to consider:
Have you actually spent time on a narrow boat, especially in the middle of winter? It might not appear so rosy when you are iced up, with a full toilet tank and no water.
Have you considered where you are going to moor?
Or are you going to keep moving around the system?
Are you working or retired? If working will continuous cruising suit your needs?
Do you actually know how much running a boat will cost you? Many think that it is a cheap way of living, but it can easily be as expensive as running a flat.