Sorry, but that is not correct. Look at schedule 5 to the ANO and at the table under paragraph 2 of the Schedule. An aircraft requires "Radia navigation equipment capable of enabling the aircraft to make an approach to landing using the Instrument Landing System". This applies to making an approach to an aerodrome "... notified for the purpose of this sub-paragraph".
So which aerodromes do you think are "notified for the purpose of this sub-paragraph"? I can't find a single such notification in the AIP. It's unlikely to include airports outside controlled airspace. It would make it illegal for any aircraft to land at the airport without an ILS receiver, regardless of circumstances. I can imagine such a notification for Heathrow and perhaps Gatwick, but it's not going to go down well with the Tiger Moths at Cambridge, is it?
AN84 specifies non FM Immune instruments be limited to VFR only.
and goes on to say
"NOTE: For aircraft of 5700 kg MTWA or less, an acceptable means of compliance is to placard and restrict non-immune receivers to operations permitted under the Restricted Approval Category LA Class 3 (see paragraph 5.4), irrespective of the approval category for that equipment."
LA Class 3 receivers may be used for the facilitation of any flight (VFR or IFR) outside controlled airspace.