I only had school swimming lessons when k you young, but we had a pool so I turned it a great swimmer. If you don't want to do swimming lessons at least take them to the pool every week or two to build their confidence and skills. My kids always make big leaps when we're on holidays and swimming several times a day in a resort pool. I guess that's like the school holiday swim programs.
Anyway it's like stretched said, it depends on what you want for your child.