Cockney Steve,
The Bluff Cove air strikes had nothing to do with Exocet. RFA Sir Galahad and RFA Sir Tristram were bombed by A-4 Skyhawks.
Bluff Cove Air Attacks - Wikipedia, the free encyclopedia
Both sides were well aware that Exocet was in the respective inventories before the conflict.
Argentine Navy: MM38 (surface-launched) and AM39 (air-launched)
Royal Navy: MM38 (surface-launched)