Thankfully I'm on leave but speaking to a colleague tonight I gather that they can overfly London, but not low enough to join the ILS. This morning they were routeing traffic around the restricted area to join the ILS at 6-8 miles out. Somebody who is actually working might be able to provide more info..
Incidentally, I gather that the daily movement record at Heathrow has been broken on the last three Fridays but I doubt if it will happen today...