Floor plan 3 children's bedrooms single-family house - potentials?

Better not, that would be about 210 sqm,

Ahem… with a garage to the east, which might be double-sized, the building envelope for the house could become tight.

Would you also design the staircase in a next house like did, so that it leads fully to the attic?

Although I was not meant, I would never give up a full staircase to the attic again. It cost us many gray hairs during planning, but without a basement, it was worth its weight in gold.

The 550 €/cubic meter is far too little.
What is your budget for the house without the garage and additional construction costs?
Which own services can actually be provided - the materials still cost money.

Our 180sqm have 890cbm and multiplied by 550, it works out quite well for us at least.

We have a developed (north-facing) plot of 570 sqm

[*]The plot is not tiny now

I would call it rather small.

We will provide information when we have news.

At the moment, I would first only be interested in the budget and the exact dimensions of the building envelope.

I would already call it quite small.

We used to have an emperor, but nowadays 570 sqm is quite decent, for a detached single-family house about 450 sqm is considered the minimum size, which in my opinion is also sufficient. More would be more comfortable, but you have to be able to get it first.