Hi,
you have a 20-30 window immediately after you stop exercising you want to take advantage of. There is a kind of milk that is skim, but has more protein in it.
You can get that, or get skim or soy milk and add protein powder. Throw in a banana. Add froxen fruit or something for flavor, and have it right after you stop.

If that is not possible, carry a protein bar and choke it down immediately after stopping. Be careful to avoid protein bars with weird stuff in them. The ones in supermarkets are usually safe.