@Accy cyclist
Accy, I'm a qualified paddlesport coach and my best advice is to join your local club. As stated above there are as many disciplines, sizes, etc as there are in cycling.
The first boat you buy will probably be inappropriate either quite soon or within 6 months. Your local club should have loads of boats for you to try, they'll also have buoyancy aids, PADDLES, spray decks and cages for your use.
I'd also advise going on a 1* course to learn the basic strokes and a bit of safety, this will make it so much easier, trust me.
Can I just have a serious, grown up talk about weirs please.... They can be a death trap. As the water drops over the weir it goes to the bottom of the river. Some of this water carries on down stream, but some returns to the weir, this is called tow back.
You should always get out and inspect a weir from the bank. You'll usually see man made walls and structures, the river will widen and deepen, then you'll hear the noise as the water falls. I've seen people drop into a weir and get a good pasting, it ain't pleasant. The water recirculates you endlessly, man made weirs are usually a straight concrete ledge with concrete walls at the side. There is no weak point in the tow back to escape. It's the paddling equivalent of cycling up the inside of a lorry.
Never say oars.... Only nobbers say that!
This is the best river I've paddled, way better than a canal
View: https://m.youtube.com/watch?v=vttdk5GaW68