Volume,
Here are the drawings that should help with your last photo of Concorde "0001".
Not very good quality, since they're scans of xerox copies of xerox copies of microfilm ...
Prototype drawing dated July 1965, which in particular shows the location of the emergency exits.
Production drawing (two cut-outs from the same drawing at the same scale) which (schematically) does actually show the 'sloped areas' both at the front and the rear of the main landing gear bay.
Note 1 : both frame 54 and frame 60 were 'production breaks'.
Note 2 : the tanks were numbered differently on the prototypes ; tank N° 9 on the prototype became tank n° 6 on the production aircraft.
CJ