Hi I purchase these cow & gate ready made bottles www.cgbabyclub.co.uk/products/milks/first-infant-milk/first-infant-milk-four-pack-200ml-ready-to-use-bottles.html but once opened it stays to keep refrigerated. My baby only takes 90ml at the minute so a 200ml bottle is too big. If I keep them in the fridge at home then put them in a cold flask could I use them out and about for the day and just tip into his bottle for feeds?