Ebelle,,
Swim nappy is a must. Need to be considerate to other swimmers. Else bb poop and it gets into the pool, everyone's gonna curse/swear. You just need to wear the swim suit over the swim nappy, just like how you'd wear shorts over the regular diapers. If u hvnt bought the swimsuit, can consider buying one with attached swim nappy. I know gymboree's swimsuit has that.
As for the warm suit that looks like a wetsuit, well, if u swim in the late afternoon abt 4pm, the pool wldve been sufficiently warmed up. Temperature shld be fine. If you swim at 8-9am, will be cold. The earliest I've brought my girl to swim is 10.30am.
Next, buy a bb sunblock. I use California baby bought from BP Thread for $28. Ask abt the expiry. Best if 2yr. Cos unless u bring bb to swim v regularly, or if you hv a bunch of kids, you won't be able to finish the tube and it wld hv expired!
Finish the tube.