I found the following list of airlines and the terminals where the are handled (information was obtained from the BAA website):
T1: El Al, Aer Lingus, British Midland International, British Airways (European flights), Cyprus Airways, Finnair, Icelandair, LOT Polish Airlines, SN Brussels International, South African Airways, Swiss Air Lines, Virgin Express.
T2: Aeroflot, Air Algerie, Air France, Alitalia, Austrian Airlines, British Midland International, British European, Croatia Airlines, CSA, Iberia, JAT Yugoslav Airlines, Lybian Arab Airlines, Lufthansa, Luxair, Malev, Olympic Airways, Riyal Air Maroc, Syrian Air, TAP Air Portugal, TAROM, Transaero, Tunis Air, Uzbekistan Airways, Yemen Airways.
T3: Air Canada, Air China, Air India, Air Jamaica, Air Mauritius, Air Namibia, Air New Zealand, ANA, American Airlines, Bangladesh Biman, British Midland International, British Airways (MIA flights), BWIA, Cathay Pacific Airways, Continental Airlines (operated by Virgin Atlantic Airways), Egyptair, Emirates, Ethiopian Airlines, Eva Air, Ghana Airways (bankrupt?), Gulf Air, Iran Air, Japan Airlines, Kibris Turkish Airlines, Korean Air, Kuweit Airways, Lithuanian Airways, Malaysian Airlines, Middle East Airlines, Nigeria Airways (bankrupt?), PIA, Qatar Airways, Royal Brunei, Royal Jordanian, SAS, Saudi Arabian, Singapore Airlines, Sudan Airways (?), Thai International Airways, Turkish Airlines, Turkmenistan Airlines, United Airlines, Varig.
T4: British Airways (intercontinental flights/ UL flights. UL=SriLankan Airways), Kenya Airways, KLM, Qantas, Sri Lankan Airways).
From all this I've noticed that most airlines I want to photograph are handled at Terminal 3. As I will most likely be spotting on T2 (Queens Building) if I go, I would like to know if these aircraft can be photographed from the Queens Building? Does anyone know what the frequency of the flights of Air Namibia, Sudan Airways are? I would like to photograph these airlines as well (if they still operate to LHR).
Will all aircraft arriving/departing LHR taxy in front of the Queens Building (T2)? Will a 300 mm lense be sufficient to photograph taxiing aircraft from the Queens Building (T2)?
Any help is very much appreciated.