[A930Rocket]

Either the switched outlet is hot on the top and bottom or is a switched half hot, meaning the upper or lower is always hot and the other half hot when switched on. Code requires a light to come on when you enter the room, via clg fixture or a light fixture on a wall outlet.

You could make the single gang switch a two gang, having a switch each for the outlet and the fan. Run a 3-wire so you can have a switched light (then you would need a 3 gang switch).

What's above the office ceiling? Attic space would make it easier to access. You could run the wire from the switch up to the attic and then over to the fan. You can nail or screw (better) a 2x4 or 6 in the attic between joists to mount the fan on.