Autopilot, GPS, ILS in FSX for default Cessna 172.
Departure: EGVN Brize Norton. UK.
Destination: EGBB Birmingham. UK.
Automatic approach for default Cessna 172.
The final approach (the glidepath) should be supported with the throttle and the flaps.
Everything else will make the autopilot.
There is no automatic changing speed in this aircraft , so you have to work with the throttle.