Have you got a little cool bag that you can put freeze blocks in it?
When I go out and about I put mine in bags and then between at least 2 large ice packs in a cool bag. So that would probably work for night time
@Georgina OK I have a insulated lunch bag! I can put it in their. I was just worried about the milk staying fresh overnight
You could get one of these https://www.instagram.com/cereschill/profilecard/?igsh=MjgyaHZmbGFldGNt