The given design options have one ground floor plan where i went 800 mm down to give a mezzanine floor above the kitchen and bedroom. The second plan shows mezzanine floor plan where the given furniture layout shows a sitting space and a bedroom. But according to client's requirements it can be changed also. The space can be also used for study or bedroom or informal sitting area.
The area below the stairs can be used as racks for books and other decorative elements (as shown in section) or can be used for storage space.
All the measurements written in plan are in MM.