Not quite. BA, LOT, Delta, Air 2000 and Air France/BritAir go form North, all others from the South. There is an EI codeshare on some BA flights in the North Terminal but EI themselves go from South.
There are a few BA flights (ex CityFlyer) still going from the South Terminal but these will also switch to the North later this year.
She's as nervous as a very small nun at a penguin shoot.