So I did this canoeing activity on the Dordogne during my Sept/Oct RS tour. I had been kayaking several times in the past and this wasn't as easy as I thought it would be. It was a bit different in that we had flat bottom boats and single-ended paddles. Wasn't quite as easy to steer as I remember from kayaking. Also, the river level was quite low and several in our group got stuck over the rocks. Thankfully I didn't get wet, but one of the people in our group did when he was trying to help he and his wife's boat off the rocks.
They do give you dry containers, which are essentially giant plastic mayo jars--people kept their wallets, phones, socks, and sunglasses in them.
Recommend non-slip shoes you don't mind getting wet and a small towel just in case. And while it wasn't windy on the river, it was slightly breezy and cool, so depending on the time of year, you might want to dress in layers, including a light sweater or jacket. And don't forget the sunscreen!
It was pretty exhausting, and while it was a beautiful ride, I think one hour vs. two would have been plenty.