PhineasC.. After a lifetime in ATC I never heard of an aircraft in the air hitting the ILS! The point at which aircraft establish on the ILS is determined by the radar controllers and can be anywhere from 6 to 20+ miles from touchdown.
The point at which aircraft are transferred to Heathrow Tower is variable and is not until the aircraft has reported fully established on the ILS.
Airplane is an Americanism. Aeroplane is preferred I suggest.
Sam Bee. The holding areas to which aircraft are cleared depend on their routes into the UK. Traffic from the north goes to Bovingdon. This includes internal Shuttles from Scotland, Manchester and also trans-Atlantic traffic using northerly routes. Traffic from the east goes to Lambourne; that from the southeast to Biggin and from the west and southwest to Ockham. As already mentioned, when one particularly hold is busy (or full up) traffic will be directed to one of the others.