The 107.5m for Cat I, II and III is a minimum distance. It may need to be more to avoid interference to the ILS signal.
You can carry out work outside of 77.5m from the runway centreline on a Code 4 F runway provided it is a non-precision or non instrument approach where a minimum 75m from
runway centreline applies provided the visibility and cloud ceiling permits arriving aircraft to operate visually. As you say provide the works information to pilots via ATIS or radio comms. Also a Notam could be issued.