Our AIP says:
Pilots should inform ATC about any intention to conduct:
a. an approach with minima less than CAT I; or
b. an autoland procedure.
When the cloud ceiling at or above 600FT or the visibility is 2,000M or more, such information must not be taken as a request for or expectation of the protection of the ILS but to enhance the possibility for ATC to inform the flight crew of any known or anticipated disturbance. If necessary, ATC will use the phrase “ILS CRITICAL (and/or SENSITIVE) AREA NOT PROTECTED”.
Protection occurs automatically below 600/2000.