Gatwick outbounds also fly over central London as do the long hauls from Europe.
Only LAM and CLN SID's
I also live in London to be exact, i live exactly below the ILS for 27R and noise is not a Problem.. I don't know what pollution does to us but the noise is not much. I would like to see something like Atlanta in the UK, busy as that.. I seen the ILS on Airnav and there's like 15-20 a/c on 5 Runways ILS. As for moving an airport... That's going to make Heathrow ten times as worse as there will be no ivestment into the Airport.
I say just expand Heathrow so there's room to accomodate more traffic.