Can my 8 month old use the swimming pools and do they sell cartons of cows milk on board?
There is a splash area on Harmony of the seas that Babies in swim diapers can use. This area has some water features and a small slide. The water in this area is about 2-3 inches deep. Keep in mind this area does opperate under more limited hours (last time I was on board it was usually around 8am- 5pm) so make sure you check that out and factor the timing into your plans. That being said, your little one will not be allowed in an of the actual swimming pools on board.
Milk is available on board free of charge. It is always available at breakfast and you will just need to ask for it if you need it at lunch or dinner.