To carry milk, or not to carry milk, that is the question?
Carrying milk adds weight to any set up plus will require a decent container. Having all your gear smell like cheese is generally not a desireable attribute. On the other hand, a splash of the white stuff in your cuppa makes it lush...
If you want to minimise carried weight, or have problems with lactose, try this alternative hot chocolate recipe, which in fact is probably the most traditional and authentic hot chocolate recipe in the world (think Aztec);
Mix five heaped teaspoons of cocoa powder with two or three heaped teaspoons of sugar. Add 1 cardamom pod and 1/8th of a teaspoon of powdered cinnamon (or use cinnamon stick). Pour over with boiling water. Stir thoroughly. Delicious. This can also work as an alternative to having milk in tea and coffee (chai/spiced coffee).
Cinnamon and cardamom are easy to carry and have an extremely long shelf life. They can also be used in many other recipes.