Marking my place for the mushroom roll recipe! Looks great 
In terms of freezing, I would definitely think that you could freeze the filling, and then defrost as needed and wrap in pastry and bake.
I suspect it would also be fine if you made the filling, allowed it to cool (so the pastry doesn't start to melt/cook) and then made up the rolls and froze them uncooked and unglazed. Could probably glaze, then bake from frozen then?
IMO pastry is always better cooked fresh rather than reheated, but you could make & bake then freeze and give them a couple of mins in the oven after defrosting to perk them up a bit. You certainly won't kill anyone, it' s just whether the pastry texture suffers from being cooked/frozen/cooked.
Waffliest answer ever 