So the plan you've posted is a basement flat that needs to be incorporated into the rest of the house? Is that correct? It might help to post the ground floor plan too.

I posted this a while ago when I tried to keep it as a granny flat. Mortgage is impossible so I need to turn it back.

The top 2 floors are fine the bottom 2 need reconfiguring but mainly the basement.

Would you consider a double height extension with stairs linking the two floors to the garden and then a wc could go where the stairs would have been? Incorporating the current kitchen, bathroom and extension would give you the most ergonomic kitchen space. I would also remove the dining room hall wall and open the front room dividing wall too and blocking up the current bedroom door.

Would have loved it, but it’s a terrace. We can add an extended extension to the basement but no higher

One option …low partition between cook’s area and dining…pantry would need a ’pretty’ side….