Originally Posted by
Globaliser
The normal position at LHR is that if you do not have a boarding pass for a flight departing from a particular terminal that day, you will not be able to get access to the airside departures area in that terminal, and thus cannot use any lounge in that area (including the QR lounge at T4).
completely correct. you can only lounge hop within terminals.
In T3, my favourite is BA Galleries First as generally it is very quiet, good drinks and magazines selection, as well as the normal a la carte menu.
On getting from T3-T4, airside, it is done by buses and landside done by the Heathrow Express. If i were short of time i'd probably come landside to do it as the buses and flight connections can be slow, especially if you have priority lane access