Hello & welcome!
Best bet is Google. From memory canals tend to ask for money, although if you are eletric you might get away with a freebie (I know canoes are free). Places like Loch Lomond & Windermere are really strict about registering. Others it depends who owns it. (Eg. Loch Earn I think is something like as good as free if you are "unpowered" (sail ore oars), a half sensible fee if you are small power and "How
much???" if your engine is > a certain horsepower that I can't remmeber (50 rings a bell)
If you are talking "competency to drive" as opposed to "fee for use of the waterway" - that will will also depend where you go. Most just ask to prove 3rd party insurance.
So in summary it varies greatly from place to palce. If you have somewhere in mind stick a post up & someone here will know the answer!