For on-the-go convenience, UHT full cream milk in those small individual cartons is really the way to go, no hot water needed, no fridge required in our heat, and you can just toss a few in your bag. Greenfields UHT full cream milk is a popular one among mums I know, and Meiji is another solid option that's widely available at most supermarkets and convenience stores. The main thing to check is that the ingredient list has only one item, full cream milk, no added sugar or milk solids, just keep it clean and simple. My friend actually mentioned that Greenfields comes in smaller 125ml or so portions which are perfect for toddlers so you're not wasting half a carton. One thing worth keeping in mind is to try not to go over 500ml of milk a day once they're past one, so the smaller carton sizes actually help with that too.