G-BOAB's cabin was removed in 2000 as pat of the project rocket upgrade where the BA fleets interors were being refitted. Rather than being binned, some parts form the original front cabin of AB were indeed put inside G-BBDG...rather than going to landfill...good Save!
As for the T5 roundabout; if you are ever there they is a road tunnel that runs under it, so its not designed for 65T of Concorde sitting on top of it.
The magazines are in the front cabin. They were used as ballast when she was used for "storing" engines in her nacelles.