We swim. We just do payg things at the leisure centre. Still not at stage can prebook termly things yet. So drop in is ideal.
We do aqua tots which is in the pool with a swimming instructor who teaches you things to get baby comfortable in water.
We also do sing song swimming which is a rhyme time type thing in the water which you splash baby and do actions etc.
Id reccomend both. Worth a look at doing something like that before commiting to a big block booking.
We did a few baby yoga classes. It was a combo of stretches, meditation, relaxation and baby massage. I enjoyed it. It was chilled.