Financing house construction with KfW funding

Good day!

My wife and I have received a bid for a plot of land in a new development area. Now, of course, it's about the finances. We have a monthly income of just under €4000. At the moment, my wife is still on parental leave, but from August 21 she will be working normally again (25 hours per week) and the little one will go to daycare.
We have a total of €60k in equity.
We had a townhouse with 130 sqm calculated and it is expected to cost €200k (complete roof is DIY, floors and painting work as well).

At the stated amount, without the incidental construction costs, which are usually between €10k and €20k... Now to my actual question:

Is it worth applying for the KfW subsidy with such an amount? The subsidies all sound great, but is it worth it? Can you already help me with something like this, even though I don't have more detailed information yet? It will be at least a KfW 55 house, possibly also KfW 45.

Thank you for your answers!

There are KfW55, KfW40, or KfW40+ in program 153. Especially with own work as you describe, you need to think in advance about who will issue you these certificates (for the loan application as well as after the construction - energy consultant, architect, or similar). Whether it is worth it can be calculated by your financial advisor. The application goes through your financing bank anyway. Depending on what interest rates/interest rate locks they can offer you or for what term you finance, it may or may not be worthwhile. Not to be forgotten is of course the current repayment bonus! It is also important to know that there will probably be new KfW funding starting July 2021. Depending on how far along you are in the planning, you will then receive the old or new conditions.

What does it mean that the entire roof is done as own work? The amount sounds incredibly low to me, we also have ancillary construction costs of 45k and not 10-20k. If you are building Kfw55 anyway, the Kfw loan with 18,000€ gifted is definitely worth it, why not? I don't know Kfw45, you mean Kfw40. Whether it's worth it, I don't know. With our solid house, the extra cost was significantly higher than the subsidy and the little bit of energy savings. But it may be different with a prefabricated house.