FYI, DL sells simulator time to the public at its museum next to ATL airport. I don't think they have a 747 simulator and it's obviously not BA, but with advanced planning (check about opening hours and sim reservations, which are not included in the price of museum admission), it's easy to organize if you're traveling through ATL. [To get to the museum from the terminal requires a taxi/uber or perhaps use of the airport Hilton's "free" shuttle bus plus a short walk.] The museum itself has a 747 on display outdoors that you can enter.