A mech should last 4 months.
Do you have a friction override on your gear levers? Is so you can fit any spare, even a steel SIS from some kids bike.
I would suggest brake and gear cables, drive side spokes, kevlar emergency spoke, brake blocks, at least 3 inner tubes, possibly one folding tyre or at least a tyre boot. Possibly a spare pump (the smallest plastic one you can find).
A 5mm allen bolt, some zip ties, duct tape, wire and superglue will repair anything else.