There will be no autoland warning if G/S signal is lost below 100ft RA or loc signal is lost below 15 ft RA - autoland will use inertial reference instead of ILS beams. However if one has a really bad day and both main and stby localizer transmitters pack up just at touchdown, autopilot has to be disengaged after touchdown and manual rollout has to be done - not an easy task with 75m RVR, but not impossible either.