Feasibility Single-family house - Cost statement / Financing realistic?

Outdoor area 25,000€ --> own work or do you want to have it done? If you have it done, that won't even come close.

Depends on what you want. o_O
We have a simple paving in front of the house and under the carport/shed (about 110 m2 + stair landing with a few palisades), paid around 9,000€ for that. And now we're having the rest of the house perimeter + terrace paved with somewhat nicer stones, also everything leveled so we can sow grass, for just under 6,000€. So in total you're at 15k – with the 25k you'd even have 10k left for a bit of garden landscaping.

The thread here is about whether a construction project is realistic, and if someone doesn't find a building project realistic just because you don't budget 40k € for the garden – well, then I don't know anymore either.

Depends on what you want. o_O
We have a simple paving in front of the house and under the carport/shed (about 110 m2 + staircase landing with a few palisades), paid around 9000€ for that. And now we're having the rest of the house perimeter + terrace paved with slightly nicer stones, and everything leveled so we can sow grass, for just under 6000€. So you're at a total of 15k - with the 25k you’d still have 10k left for some garden landscaping.

This thread is about whether a construction project is realistic, and if someone finds a project unrealistic just because you don’t budget 40k € for the garden - well, I don’t know anymore.

I also think you can still play around quite a bit with this item. By the time the outdoor area is due, all other costs should be largely known, so the outdoor area can be planned depending on the remaining available budget. Doing it yourself is of course possible.

I also think that you can still play well with this position. By the time the outdoor area is due, all other costs should be largely known so that, depending on the remaining budget, the outdoor area can be planned. Personal contribution is of course possible.

Yes, we did exactly that.
We put our budget planning into a somewhat more elaborate Excel sheet. And some items were buffer-dependent.
We didn’t have a lot of capital and the option to plan with an extremely large buffer. Our buffer was basically: If something goes wrong, we’re not out, then our cars just stay on gravel for a while and there’s still dirt behind the house.
In the end, through a mix of luck, careful planning, and economical sampling, we still had money left to make the outdoor area acceptable for the time being and to save a bit more. But even with less luck, I’d be glad to have built. We would still have a roof over our heads on our own land and be paying into our retirement, not the landlord’s.

I also think that you can still play well with this position. By the time the exterior work is due, all other costs should be largely known, so that depending on the remaining available budget, the exterior work can also be planned. Own contribution is of course possible.

Good to hear that, when you always read the comments here, you almost have to be a millionaire to even consider building a house.
Such a large project never goes without risk, but since I am more of a "safety type," I want to know most things in advance and have buffers planned.

a little hint regarding the wedding that will just 'happen' within the next two years: If our incompetent politicians allow proper celebrations again by then: That will cost a lot of money. 20k gets spent quickly.

A proper celebration for us = 10k Gifts from the guests = 10k

It works without a 20k "loss"

Proper party at our place = 10k
Gifts from the guests = 10k

It’s possible even without a 20k "loss"

Party with 50 guests at our restaurant in the countryside and by the water: in 2018 we paid all in 8,500€ for the wedding. 20,000€ wouldn’t have been wise in that situation.