I sometimes freeze DD's bottles in correct feeding amount, freeze then remove from freezer before bedtime and place in fridge. In the am, just take the cooler to school with him...and it goes back into fridge until his feeding time. Our drive to school is <10 min, so I don't use a freezer pack. Considering how long it takes the milk to thaw, I wouldn't think you need an freezer pack unless you were on a road trip for a couple hours with the frozen milk.