it depends if your daughter likes to be confined. My son didn't like to be confined (he hated strollers)...so I just got him the arm float..but hubby and I just carried him throughout the swim.

I suggest buying the suit that keeps the baby warm in the pool. I bought it from Mothercare..i think that is really useful so that the babies can be in the water for a longer time.

it's a suit..with velcro..i think can fit your daughter..as they come in many sizes. furthermore..you'll be putting this over her after she used her swimming suit..so i'm sure able to.

sunblock lotion..don't forget that too! and if you can find swimming diapers..would be good too (i used normal diapers..couldn't find swimming diapers)