The two arms of the L shaped floorplan have been assigned, one for the day living and one for the night.
The long corridor you found at the entrance has been now divided into four “niche”: the first is for the entrance area and the others are respectively for the kitchen, for a little library-office room connected to the living room and the last is a laundry room.
It is preferred to maintain the structural wall of the existing corridor, making only the required holes to access to the rooms. This made possible to open the living room in a single space, divided only functionally, in three parts: the first ,near the kitchen and the entrance, has a table for eating or to welcome visitors and guests, a second zone with sofas around the fireplace and a third zone to watch tv.
This space can be isolated from the other activity by the decorative sliding doors of Rimadesio, as proposed on the plan.
Without detailed structural information, for that initial phase, it has been better to maintain the existing fireplace: a new hood in plasterboard straightens the current wedge, and visually divides the living room in two.
In the blind side of the fireplace, on the new base covered in Marquina black marble, you could place the TV.
The centre of the night zone of the flat is the corridor, with a “walk-in closed” function, on which overlook the master bedroom, with “en-suite” bathroom, two further bedrooms, a bathroom and the entrance to the laundry room.