DS got 8 weeks (?) swimming in P4, but only managed about 4 of them before covid struck (and another issue specific to our school that cut off a couple). He had been going since he was a baby, as it was something that was just second nature to me growing up... It was absolutely non negotiable to me that he was able to swim a couple of lengths and do water safety stuff, just in case. Luckily, he quite enjoys it.
We had annual lessons at primary ( I think) and a school funded Saturday "family swimming" thing, and secondary had a (disgusting) pool where we did lessons and safety stuff with canoes and shit at least one term a year. I'm surprised it hasn't been such an engrained thing north of the border too, as it is so important (let alone potentially life saving).