The living room wastes a lot, a lot of space, which basically can only serve as a dance floor. But that is simply due to the very large upper floor. 26m² bedroom and dressing room, 19m² children's room and another guest room, you have to actually need that first. Do guests come so regularly that you cannot pull out the couch in the living room or accommodate guests in the office?
My mother is very satisfied with the couch in the living room and is with us for about 30, 35 days a year.
I have to smile about the outdoor facilities. 25k, I will also need that for the complete outdoor facilities including garden, hedge, tool shed, paving, etc. So for materials and tools, I will do the work myself. Just for an appealing fence (no double rod mat, no precast concrete parts) you can easily spend 25, 30k. If we are really talking about a completely finished garden, driveway, etc., from a professional company, not from "Handwerk 24/7 Poznan," then you will easily be at 60, 70k and have a good standard, nothing extraordinary.
For incidental construction costs, it depends on what the general contractor says in his contract regarding the foundation. If it says something like "30cm gravel base is included, everything else costs extra," then you will probably face several tens of thousands more. House connections also no longer cost less than 10,000 EUR.