Phil - just to tidy up the loose ends..
Above 200'RA if the LOC or GS signal is lost for more than 7 seconds, the AP's disengage (with aural and visual warnings) and the FD's revert to basic modes, HDG V/S or TRK FPA. This would prompt a go-around, which is nice.
Ahhhh, THIS is what I didn't know. So AP/FD will remain in LAND mode, do "its best" using internal/inertial reference and warn the pilots via the autoland lights, correct?
Correct. Below 15'RA it can cope with no LOC signal, below 100'RA it can cope without G/S, in those cases there is no warning. From 200'RA down to those heights a big red AUTOLAND light comes on - prompting a G/A unless sufficient visual reference for landing.