Looking more broadly, it does illustrate how the advice of "buy a secondhand boat and get some experience before spending £xxx,xxx on a new build yourself" is sage. A £30-40k narrowboat is likely to be in reasonable shape, gets you on the cut, and would probably resell for similar with not too much bother. And it would be an investment in skills to learn how it all works, how it fits together, why some things are done the way they are, etc, etc.
Look at it another way, a new boat is likely to take 2+ years from now to be truly "ready". Thats a long time in your adult lifehood to be waiting for something.