Adding a ceiling light to this circuit
Neutral is required at the celing light box. You can't wire up a celing light with just the hot and ground from the switch. It will work, but is dangerous and violates electrical code.
Your best bet here is to fish a new /2 cable from the box with the switched outlet up to the celing since this box has the required neutral, (switched) hot, and ground. If you don't want half of the recepticle to be switched also, you will need to replace it with one without the broken tab or pigtail the unswiched hot wire to both halves of the recepticle.
You still won't have neutral in the switch box, but this should be ok since you are not changing that part of the circuit and it can still be grandfathered.