This is all getting a bit silly! For those who aren't familiar..... aircraft flying into Heathrow are radar controlled until they are on final approach. If the wind is from the west the usual route for traffic from the Bristol direction would be to Ockham, thence by radar vectors over south London on to the ILS for 27L/R. Normal intercept point is around 10 miles out, but this distance can vary enormously depending on other traffic. The precise routeing is entirely up to the radar controller. If things are quiet it may not even get to Ockham, but maybe "snatched" between Woodley and Ockham for a long downwind..
If the wind is from the east it would still route to Ockham, but then fly back west over Byfleet, Chobham, Scot, etc to join the 09 ILS about 10 miles west of Heathrow, thence over Windsor to the airport. BUT.. if there was a slot in the landing stream in might join the ILS 25 miles west of the airport for a straight-in approach and not go to Ockham.
It is impossible to say in advance exactly where it will fly over but anyone who is familiar with the approach patterns to Heathrow will have a reasonable idea. I can't imagine it getting near Lambourne at all.... But who knows?