idea:
Closed off lounge by creating a hallway, door to kitchen at the end. New staircase (pushed into former utility area), laundry and separate office in the garage (though could be kept one space). Side entry hallway wider for coats and shoes, perhaps boiler could be moved to wc, but/and there's plenty space under the stairs as well. Removed kitchen-dining wall, could keep chimney intact. U-shaped kitchen with peninsula. Dining area with extra storage. Sofa is lower, so placed that near the garden doors, as table would block view and 'traffic'. If tv is on your list of wants, it could go in the peninsula.
Upstairs changes: The bathroom from your previous post somewhat tweaked, moved window on the side because of shower (or simply close off), corner bath under the rooflight. Because of the new staircase i moved the bottom right bedroom door, which would allow to move the other bedroom doors as well (which makes the master bedroom slightly larger).
Hope it may inspire you!
Q