https://www.loveskirting.co.uk/flooring-thresholds-c17/by-product-c29/ramp-section-c43/solid-oak-ramp-section-threshold-0-9-metre-p121

Ask your self if the kitchen is actually a good kitchen….. if you need a utility room next to the kitchen for additional refrigeration or storage or additional work surface then it’s not a good enough kitchen for you. Ideally the utility should be just a laundry room in which case it’s best near the bedrooms upstairs or at least near the bottom of the stairs.

We had our bedroom floor done 3 years, it’s about 27sqm. It only cost c1k but we didn’t need sound insulation. The guy was an antique furniture restorer who started refurbishing floors as a sideline and i suspect he seriously undercharged us..We also didn’t need much in terms of repair work, all boards were sound and only 1 had been replaced at some point in its lifetime, you may also find holes where central heating has been installed or gaps under skirting etc i think you need to consider whether you’d be happy with all the dents as pine is such a soft wood. We hung new curtains days after the floor being done and the ladder (sat on a towel) created dents. We put furniture pads under everything but have had no need to move the furniture since but i suspect it has big dents everywhere! It's fine for us jn a bedroom but not sure if i could cope in a living space

oh old post to practice, the obvious choice is first floor extention but this only if the ground foundation on the back supports for this floor. Its mirroring the outer wall of the ground floor so enough area, there also alternative option of cantilever steel beams or concrete floor slab for first floor side extention though maybe need additional permit . Bedroom 3 will slightly Bigger than original, Plan A Plan B - Very Narrow Hallway Plan C - With Cantilever