Is milk complementary onboard?
Yes! Milk is complimentary on board.
At breakfast the milk is always available on the buffet and in the main dining room.
If you want milk with lunch or dinner in the buffet, you will need to ask a crew member and they can go in the back and get some for you as it is not normally out and available to grab. In the main dining room they can always get it for you.
If you need milk for your child during the day, what I like to do is grab an extra carton or two depending on how much you think you will need on your way out of breakfast and keep them in the fridge in the room. Keep in mind that often the fridge for lack of a better word does not always keep things as cold as your fridge at home so I would make sure you use that milk within 24 hours so it doesn't go bad.
Hope this helps!