Well I guess this forum is way more popular than I realised.
To the people wondering if I'm trolling or whatever. I'm kind of baffled. I assume you're new to the canals, because licenses and stuff, until I suppose pretty recently, were not really a thing anyone who lived on the canals properly thought about. It was more people who had a boat as a holiday home that bothered with them. There's a point with any rule where compliance is common enough that you're the bad guy if you don't comply, and there's a point where compliance is rare enough that you're an idiot if you do comply. I'm out of the know these days (in so far as I ever was in the know), and I'm just trying to find out where we're at with that. A few answers here (just a few) have actually been useful in explaining that, so that you to these (handful) of people.
My practical purpose is that I'm considering buying a boat that needs an interior makeover, and I'm costing that out to see if the level of profit would be worth it. I'd need to move it from where I buy it to where I'd work on it, so I'm just trying to see if I really need to spend hundreds of pounds just for a couple of weeks only to put in drydock where the license would be wasted, or if I could feasibly skip that, and only buy a license at the end of the renovation/let the next owner buy the license.
To the people wondering about my dad, and my age and all that, you're... weird, but fine: my dad started carrying coal in 1960 and then later passengers. He worked all over England, and then moved to Europe in the 70s. In the 90s he moved back to England, and became a trainer. He was in his 40s when I was born. I'm in my 30s. He died a few years ago, which is why I can't simply ask him this stuff anymore. I don't know why anyone needed to know that, but there you go.
Again, thanks to those who actually addressed the question. dmr especially, thanks, that makes sense of the situation.