Single-family house without a basement - generate parking space elsewhere

Definitely a double garage if possible, preferably 9x8m, then you can fit a lot in!! Without a basement, you could also build the house a bit bigger...
An attic is always inconvenient, do you want to carry everything up there or what?

Depending on the climate, only tools, bicycles, garden equipment, drinks, and the like fit in the garage... I would no longer store garden furniture cushions with us because of the risk of mold.

This applies equally to garden sheds and unheated attics. Nothing for textiles, documents, suitcases, ... and the like.

I would reconsider the insulation of the attic.

Without being indiscreet: Would you perhaps be willing to provide 1-2 pictures of your attic? I would like to get an impression of the actual space conditions.

Maybe this helps you somewhat, the house dimensions are roughly the same as yours, only the roof pitch is lower, in the middle we have about 1.75 m of standing height. Otherwise, you see here about half of the area. At the back in the shadow there is an additional length of OSB boards, about 2.25 m, which you cannot see.

From experience with such an attic.
Install a Velux to be able to properly ventilate. It is really dry for us, although partly ice-cold. Paint freezes at the top in winter, the garden cushions, boat cushions, blankets, etc. are stored there and have no damage at all. You must not dry laundry there, because with these stupid modern underlay membranes it is not drafty enough for that. Too little airflow. We also planned that, one or two attempts showed it on the cushions, it became damp. Bought a dryer, stopped drying there, bam, everything dry.
A staircase is a must, plus a small hallway upstairs, then a terrace door as the door, everything else warps. The insulation of the terrace door is ok.
It is less dry in garages than in the attic and strangely less cold. The wall paint in the garage does not freeze. I store tools, bike, cable reels, polish, WD 40, garden tools, lawnmower, an old Quelle refrigerator for garden parties and such there. All that works.
Consider why a car must also go into the garage. It is painted and galvanized and can handle being outside well. That saves money, the standard six by three gives a great garden shed, storage, workbench space, only the car then stays outside. Attached are pictures for illustration. Karsten

It is similar for us, we built a 1.5-car garage. Double-walled, but not insulated. With ventilation at the right time, it stays reasonably okay even for more sensitive items. However, when there is a weather change from long cold to 11 degrees, everything gets wet, the condensation is severe. However, there is no everyday vehicle inside. Otherwise, an extremely high amount of moisture would come in. We use the attic as storage space for sensitive items, insulated despite the insulation of the ceiling between floors. It works great, but you have to be careful not to bring in too much moisture here either. Alternatively, ventilate often. From my point of view, drying laundry is a no-go. Cheaper suggestion: condenser dryer, it partially heats the house with the dry waste heat and solves many other problems with mold!

Drying laundry in the cold basement is building physics Russian roulette. Very likely you will have problems with moisture because the air exchange is not sufficient. If the condensed water then runs into the insulation, it's a serious problem. A cold basement should also not be open too often or for too long.