Corner plot with a granny flat

And with that I currently have a real problem on the ground floor..

I can do that. For that, I now have the children's bathroom above the living room? Let's wait and see what the OP says about it. I would provide the granny flat with a flat roof. Then you can plan a really big window by the stairs.

Upper floor: 3 bedrooms, 2x office, 2x bathroom, laundry room

Even if an office is only intended for hobbies and as a backup, I find 6 sqm quite small for 4 people.
Yes, budget, but now you come with an expensive flat roof and large window on the upper floor.

I would provide the granny flat with a flat roof. Then you can plan a really big window near the stairs.

Of course, I also have the thought that one thing or another would be possible, but I think first it is necessary to plan good and affordable living space.

For me, the entrance and the bathroom in the granny flat are not appealing. The bathroom is too tiny; after all, there should still be room for an autonomous washing machine. Or rather a barrier-free shower and necessary clearances, possibly for a grab bar on the wall.
It looks different to me than for you. I suppose your bedroom does not have 3 meters of floor space on the bottom wall? I try to plan there the 3 x 4 if possible and then what remains would just be a tiny 4 sqm small bathroom, which I would plan in the main apartment, because they are still young enough and have other bathrooms available, but not in the granny flat.
What do you think? Can you manage it better?

I am still a fan of (because of the dimensions and the adapted office) ... However, the utility room, virtually also as an extended closet space in the middle of the two bathrooms, was better.

Why ... had apparently also once mentioned somewhere that for the granny flat the morning coffee on the terrace is actually important. And this east terrace of the granny flat also still receives southern sun.

The family terrace is then definitely, because of possible western sun, simply more family-friendly for me. I also like the exterior better than if you then somehow have to think of a flat roof or huge sloped roof on the left side above the granny flat in the west.

And, additionally, in post 79 photovoltaic-wise the southern exposure can take place, and if you have a very shallow roof pitch there, you can also sensibly cover at least the top row of the north roof.

Wow, you were really creative today.
I can't keep up anymore.

What can I say: That’s almost exactly the floor plan of our current house!
We would immediately feel “at home” there (okay, currently it’s only 7x10m).
And what I just don’t like is the long, dark, narrow hallway – don’t you have another idea for that? Maybe a different staircase shape after all?

I would design the granny flat with a flat roof. Then you can plan a really big window by the stairs.

But you have also planned the upper floor very small now?

For me, I don’t find the entrance and the bathroom in the granny flat appealing.

I don’t find the 3m west garden very appealing. With a hedge, there are only 2m width left – so it’s hardly usable.
Therefore, I might suggest the entrance for the granny flat on the side after all.

And, additionally, in post 79 photovoltaic-wise, the south side placement can be done, and if you have a very shallow roof pitch, at least the top row of the north roof can also be sensibly covered.

Isn’t the south side enough?

And what I simply don't like is the long dark narrow corridor

Where do you see a long narrow corridor? I actually don't plan something like that at all.

Where do you see a long narrow corridor? I actually don't plan something like that at all.

Ok, you are right, I would have given the kitchen a small wall to the corridor.