Is a home construction project realistic?

Our construction project is planned as follows:
Single-family house without basement including ancillary construction costs, 160 sqm, plot available (see above) €270,000
For kitchen, outdoor facilities, carport, etc., we are budgeting around €30,000.
So a total of €300,000

Does anyone have any opinion on our project

Accidentally sent too early.. Here again the complete text:

Hello everyone,

my girlfriend (26) and I (30) want to build our own home. I wanted to ask here if you think it’s realistic.

Key data about us:
She 26 years old, permanent contract, public service, income €1,500 net
Me 30 years old, permanent contract, public service, income €2,500 net

Both 13th salary (95%), but we do not count on that.

Our income will definitely increase in the coming years:
Key data for 2018:
Me €3,000 net
Her €1,700 net (however, desire for children in 2018 to be considered)

So summarized as of today:
Income: €4,000
Equity: €30,000
Plot of land available: €20,000

Our current expense situation is as follows:
Car payment 1 (until Feb 2018) €280
Car payment 2 (until Feb 2020) €170
Gasoline €350
Car insurance €140
Car taxes €40
Car depreciation calculation €150

Mobile phone €70
Dog (food, vet calculation, etc.) €100
Insurance (liability, occupational disability) €80
Miscellaneous €70

Groceries €400
Leisure €400

Rent as well as electricity, water, gas, etc. currently do not apply to us.

So we currently have monthly expenses of about €2,300. Surplus per month €1,700.

Our building project should look as follows:
Single-family house without basement including incidental building costs, 160 sqm, plot available (see above) €270,000
For kitchen, outdoor facilities, carport, etc., we calculate about €30,000.
So a total of €300,000

Do you think our building project is realistic? Will we get financing? Have we overlooked something?

We look forward to your answers!

Thank you!

P.S. The plot comes from the family. The plot is 1100 sqm in size. The lower price is due to the fact that the front area has a standard land value of about €30/sqm and the back only 0.40 cents/sqm.

Well, I would say it would work for us in "enemy territory," although it would be tight...
It always depends on whether you build fairly simply and maybe add some EL, or if everything has to be top-notch and you can/want to do no manual labor (as a desk jockey???).
One more thing about saving equity: due to ever stricter energy saving regulations and rising construction costs, you end up going in circles here. Our house would have been about €30,000 more expensive at least, about 3 years after signing the contract, and you have to save that diligently first.
And in the end, you save it very strictly now, but in 3 years the interest rates are 1% higher again and that doesn’t help you either...
I would look around or ask a few banks whether it is possible now, and if yes, then start now...
With €1700 (if that can actually be raised for the house (installment + additional costs) and nothing was sugarcoated) you should easily be able to finance €300,000, so that you finish before retirement...

Our income is guaranteed to increase in the coming years:
Key figures for 2018:
Me €3,000 net
Her €1,700 net (however child wish in 2018)

Cell phone €70
Dog (food, vet calculation, etc.) €100
Insurances (liability, occupational disability) €80
Miscellaneous €70

Groceries €400
Leisure €400

Rent as well as electricity, water, gas, etc. currently do not apply to us.

So we currently have monthly expenses of about €2,300. Surplus per month €1,700.
.

I no longer see a €1700 surplus here as soon as a child is on board and the additional costs arise AND only part-time work is done or and childcare.