My DC had swimming lessons at school - one term in year 4. That was it.
Fortunately they could already swim well because we had the means to pay for lessons, which they'd been having since age 3.5. By the time lessons hit, they could swim 400 metres at 3 strokes, swim underwater, dive in and pick a ring up off the bottom, snorkel with correct fin technique and float in a variety of ways. But that cost £££, and not everyone has that.