You are at say 150ft and it trips or deselects whatever.
Here I think you have to be more specific. CAT III ILS requires all 3 fully functioning Flight Control Computers (autopilots).
One FCC or its required subsystems may be(-come) inoperative and still permit an autoland but at higher minima (CAT II).
To go-around or continue will be a question of actual weather.
If you insist on a go-around I'll suggest a ground equipment failure like runway lighting, unauthorized runway intrusion or ILS failure.
the capt has his hand hovering above the throttles.
During the final approach the capt will have his hand
on the
thrust levers with a finger (thumb) ready to press the go-around button.
Given the fact you have a full payload,but not heavy on fuel, could you pull out or would the aircraft not respond in time?
No worries, mate
That is, it will start to climb using only moderate thrust - stabilizing at a climb rate of 2000'/ minute to the preset go-around altitude. Gear is normally retracted when climb is indicated and flaps left extended untill final go-around altitude (the flaps part may vary from operator to operator).
Would you get a warning that the autoland has tripped?
An onboard system (or ILS-signal failure) will show up in the ASA, autoland status annunciator, as an audible click and display of NO LAND 3 and LAND 2, indicating that the system has degraded to CAT II but still capable of autoland. - if remaining systems are OK.
If even a a lower altitude it fails,would you then just continue the landing even though you can't see a thing?
Only CAT III with no decision height permits landing without any visual contact at all.
If the go-around is initiated very late (just before touch-down) the wheels may actually touch the runway before the go-around climb is established. Legal and safe.