my suggestions (subject to accurate dimensions) include the new ensuite with extra wide mirror doored wall cabinets) a dressing area in the hallways adding a biw to the small bedroom and updating the family bathroom would allow for more generous shower and vanity and a handbasin in the toilet (and the small rectangles in the dressing area represent chests of drawers)

Hi Badobbs Structafloor will only span 600mm unsupported in the 22mm and 450mm in the 19mm version so no, it alone won't fix your issue. A simple fix would be to pull up the floor in the affected area and then 'pack' it up to level, THEN lay some structaflor over the new supported sub floor. This is done by getting a laser level and marking out the low points in the joists then making up packers to suit, or installing a packer and planing it down to suit. It depends on the level of dipping. It will be your cheapest option and definitely a job for your carpenter (unless you're handy). Regarding disturbing the floorboards that is nonsense. If there are other issues such as other sagging floorboards then you can address them at the same time, or fix them down properly with screws. I suspect that the real issue is that the wall removal did not take into account that the floor joists are usually fixed to it and they are now unsupported. If you get under there and find issues with your joists/bearers then it is not a big deal to install a couple of stumps/connect bearers to support them whilst it is open. We do it all the time. Either way laying a new floor over a subfloor without addressing it would be a waste of money and will degrade your new floor. Cheers

Gorgeous brick pavers, I love that look for the floor! It has a rustic appearance yet you're right- sophisticated, even an elegance. I think this would suit the feeling I'm wanting for the room, the pine boards have a rustic appearance, this would go well with them. We have a 1m square oak table with cross back chairs for the dining section and a La Spezia 3 light pendant (Beacon), farmhouse sink, timber hood cover to give you an idea of the look we're going for. Thanks very much for your thoughts on this. I like the idea you're going with, but yes, we have the window and door in already. Door could be trimmed if necessary. It wasn't until the window was already made and the wall sheets and cladding was removed that we realised the original kitchen layout had the back door next to the window, and the door into the laundry section was a modification. I most likely would have put it back where it was originally or had double doors. It made no logical sense for the back door to be a thoroughfare through the laundry, eliminating valuable storage space. I may have just left the kitchen in the original layout and made an entry into the laundry from the kitchen side for a laundry/butler's pantry with fridge in there. Removed the side window for more wall space for storage and changed the existing door to a window. But it's too late now, the outside of the house has all been newly clad so doors and windows are as is. There's no other possible place in the house for a laundry. It is a very tight space. Plan to build an external laundry studio in the future. The one in the house would be temporary, yet need it to accommodate a washer dryer combo for now, and be suitable for prospective buyers/renters in future if the external laundry doesn't eventuate. This is the original 1960's floor plan. A previous owner made internal access into the laundry and made bench space where the original back door was, the next owners opened up the living to dining room and blocked up the hallway doorway which became the fridge space. The cornice didn't match up in the hallway though where the old doorway was. They had made a shelf from the cut out on the hallway side, and the protruding section in the kitchen side became a kind of bulkhead for the fridge. Old hallway We've rebuilt this so that it could have an upper cabinet on the kitchen side/ hallway later if needed. But the lack of space in the hallway didn't allow us to build a linen cupboard, so that will also be needed to be included somewhere in the house. At this stage, thinking we will have to configure the laundry space to have a linen cupboard/ broom cupboard between the dining room and laundry section. Open to ideas too for storage in that limited laundry area space. I'll add more measurements to the floor plan for reference.

I agree that it can be upsetting at this stage but your timber will all darken naturally and the difference will become less obvious over time and once you have furniture and rugs in place it's likely to be one of those issues that only you and no one else will notice. And I defy anyone to not have something like this in their house which has been newly built/renovated. I know this isn't terribly helpful but I don't think ripping anything up to start again or going to great lengths to seek recompense from supplier/installer is going to help your blood pressure either (by all means raise concerns with them and ask for suggestions from them).