Yeah I saw the one in Brentford the other day, they quite often pop up there so worth nipping In as well.
When we first moved onto boat we fully broke the rules and rented an old tub for far too much money, it was all good though as we were fully aware of the risk that we decided to take, we knew that we had little in the way of tenure and insurance and that was good for us. It gave us a stepping stone to buying our own boat. The only niggle, or worry that I had is that if the boat we were on caused damage to someone else.
I would not advise for or against but would urge you to know exactly what the risks are and the rest, is up to you.
Oh, and if you do decide to take this route, keep yer head down!