I agree delay is plan #1. But if you rout them, and you have the means a clean up operation to gather up all loose equipment left on the dead, finnish off or interigate the wounded ( assuming you can speak the language, or the medical facilities to keep them alive to be interogated by the home army-if it ever gets there). Make sure your troops expect no quarter and give none.
WASTe of recources?
Heck this is the best use of the civilian home gaurd types...to absorb the brunt of the enemy advance, make them bleed, slow them down and possibly stop them.( very likely in this scinerio) Then the professionals can mop up.
In other words flexability and simplicty should win the day.
Remember the enemy Has no airplanes...you do.
Most of all you need a caring yet ruthles, cold, respected, calculating commander