How does a bog standard PPL tell the difference between a PTT switch and the A/P disconnect button on the yoke?
Ask the cabin crew! Certainly in our company they are encouraged to come into the flight deck and learn where the PTT is (there is one on the pedestal as well, using that there is no chance of inadvertant autopilot disconnect!), normally we also show them how to set 7000 on the transponder.
In a modern airliner the route will be in the computer right up to joining the ILS so mainly a case of reseting the altitude and speed then engaging approach mode, you could be unlucky and not have the arrival programmed in but I would say you could be talked through that easily enough!