Things to consider
You will need a licence for the navigation authority for the river or canal that you plan to be based on, and visitor licences for any waterways in different navigation authority ownership that you may wish to visit.
If you want to live in one place, so you can attend college or get to your place of work, for example, and not be continually moving your home around, you need to find a mooring (preferably before you take the plunge and buy a boat). Suitable moorings in popular areas such as London are scarce and can be very expensive.
Alternatively, on Canal & River Trust waterways you can declare yourself as ‘continuously cruising’, which means you don’t have to pay for a mooring, but you will need to move your boat at least every 14 days (sooner if moored at a visitor mooring which specifies a shorter period). And this doesn’t just mean moving round the bend to the next road access point. If you have a job based in one place, or other local commitments such as school for your children, this isn’t a practical option, and you should look for a permanent mooring.
In order to obtain a licence you will need to take out at least third party insurance. However, if all your worldly goods are on board you may wish to take out full insurance on the contents too. Boat fires and boat sinkings are both things that can and do happen. Boats also tend to be less secure than houses and boaters often find things stolen from their roofs or decks even if the cabin hasn’t been broken into. If the boat is more than 20 years old then most insurance companies will insist on regular hull surveys (out of the water) – a considerable expense.