All kosher meals are from Hermolis ^^
Terminal 1: Soup and filled bagels available in the international lounge (the one they use for TLV flights).
Terminal 3: KSMLs only available in the First lounge - not the Club lounge area.
Terminal 5A: KSMLs available in all lounges. Soup and bagels in the Club lounges and full meals in Galleries First and Concorde Room.
Terminal 5B: No KSMLs in the BA lounge.
Terminal 5C: No BA lounge! You can get up to £15 of stuff from Starbucks if you show then a Club or First boarding pass. They might have Walkers Crisps (check for LBD Hechsher) - plus soft drinks and tea/coffee.
In my experience T1 has full meals available also on request - last week had omelette/potatoes/mushrooms etc for breakfast, and for dinner choice of meatballs and spaghetti, chinese chicken and rice or salmon and mashed potato. All very good (apart from omelette which I find inedible).
Also KSML available on request in CX lounge in Hong Kong, QF F lounge in Sydney and SQ Private Room in Singapore. All must be requested in advance.