Question about milk....?

We are planning to go down to the beach for the day tomorrow. I have some milk that is freezing right now. Should I thaw it in the freezer now so its good for the morning? Also what do I have to do for tomorrow? Keep it cool? What should I do for when we are down at the board walk..can I warm it before we leave and leave it sit for when he is hungry? How long can milk sit out for once it has been warmed?