Casper, I'm not aware of any fuel tank protection by either BA or AF prior to the accident.
Overweight & aft GC was due too much fuel as well as captain authorising baggage to be loaded (in the rear baggage cabin) when the aeroplane was already about 5 tons overweight.
Something else germane to the accident was that the fuel tanks were overfilled leaving no airspace to absorb any shock waves on the basis this extra fuel would be burned off during taxi, but the change of runway (to a downwind one) meant a much shorter taxy so it wasn't burned off and the FE didn't ask for a delay while it got burned off. They just 'went'.
Worse - realising they had a rearward CG, fuel was being transferred from tank 11 (in the tail) to the wing tanks DURING THE TAKE OFF ROLL. an absolute no-no in Conc ops. The idea being as fuel was burned off from the wing tanks and replaced by fuel from tank 11, the CG would move foreward.
The result was the wing tanks were always overfull even though they were supplying fuel to the engines, so when one tank was hit by a big piece of tyre the shock waves travelled up through the fuel, bounced off the top surface of the tank, having found no gap of compressible air to absorb the overpressure, and travelled back down and burst the tank floor from inside.