Of the aircraft I have flown the one that that is the most capable of an automatic landing set up by a novice is a Fokker 70/100. A little bit of radio work, press a few buttons and that's it. The braking would be the hardest bit.
As for passing out, food poisoning, meningitis etc. Oxygen deprivation is really a bit too far fetched and few cabin crew will not know how the masks work in the flight deck. Also have you considered how they will get entry to the flight deck? Now given a simple radio setup like a Fokker's, a person with little or no flying experience might be capable of being talked down anywhere with an ILS; CAT I,II or III.