House construction - can I pay for it on my own?

hello! i just signed up fresh because i have a question. first of all: currently i live alone with my 2 dogs in my former parents' house, about 200 sqm. i don't even use all the rooms and have incredibly high additional costs (440 euros/month). i pay 'only' 650 euros warm rent to my father, but i simply can't and don't want to afford more.... besides, the house is supposed to be sold in 5 years at the latest and i have to move out. now my father has offered me a plot of land if i build a house on it. that actually comes as a big surprise, because i'm not even 30 yet and don't know if i want to commit so firmly now. i do have a boyfriend who earns about as much as i do and is also in permanent employment, but it's not clear yet if we want to move in together. it's all still too fresh. my parents said i wouldn't find a rental apartment anyway with 2 dogs, and an owner-occupied apartment would be nonsense too. i haven't looked around yet because until yesterday i didn't know i have to move out now. now to my question: how much may the house cost (all in all) so that not more than 600-700 euros INCLUDING additional costs come out? (energy-saving house) how do i calculate that? and what do i have to consider? i have no equity and no building savings contract. net income 1600 euros. i would like something around 110-120 sqm. i am not married and want to finance alone. is that possible?? or is looking for a rental apartment smarter?

hello,

I firmly assume that it will not work with 600-700€ including additional costs.

For 110-120 sqm you would have to expect at least 140T€ - 180T€ with a basement.

Furthermore, although the interest rates are still very low, it will not work without equity.