Here you have my proposal for adding a new room in the flat. While working on it, I realised 2 possible proposals for the room. Both take the new space from the living - room. The first solves the new space with furnitures and a new layout with furnishing, the seconf one with wardrobes in the dividing room walls to gain some space and make it more clean. In both I opened the kitchen, making the living - dining and kitchen space one open space with a bar that divides the kitchen from the rest. That makes look the house bigger and you don't need the destroy the old kitchen, just enlarge it and maybe changing the tiles, as you feel.

It works, it's cheap, it makes the house different, the living room - kitchen is really practic and it looks big.