Hello,
I think there was a list made somewhere for the "problems to look out for", a few from the top of my head:
Rusted/rotted king pins (due to lack of greasing), electricals (usually bad connections/corrosion of earth points), leaking oil from gearbox around the half axle rubber boots, leaking oil from engine at oil sump,valve cover. BISs also need to have the cooling system serviced regularly as they can overheat and have cylinder head damage (need to check when the coolant was replaced, make sure it's topped up, make sure the thermostat works porperly and that the cooling fan turns on when needed.)
There's also the usual things: tyres, suspension (bushes, ball joints, shocks), brakes, steering.
Rust can be found at the bottom of the car all around (outer an inner wheel arches, outer and inner sills bottom of boot, edge of floor pan,bottom of doors, worse if it's rusty around where the suspension bolts onto the chassis.)
The way i check for structural or surface rust is with a screwdriver (if it goes through it's structural

)
That's all i can think of, good luck with your licence.