anyone know if there is a later period suplement for barons war? or else something else that has rules for late 100 years war of roughly platoon size, that is c. 30 men each side.

Always really liked that general game scale. You have enough units for combined arms and separate groups, but still low enough that each model feels like they are doing something. Also just so happens to be a good scale to depict an indivigual lords retinue and is the rough amount a commander could control in detail.