My project relied on low costs of this reconstruction, which you mentioned , so I tried to find solution with minimum demolition and brickworks and work with plasterboard. I think that just turning kitchen into another bedroom is that one with the lower reconstruction. But if you want some more space in the living area , you will have to "move" kitchen wall untill the window in new room so, you will have a little bit of demolition. I made not so mothern space, but functional for familly and much more colorfull then was before.You have drawings for both version, so you can see which is for you the best.