Hello colongne152. It depends. According to the wording of the contract (if your explanations are complete in this regard), the "Financing Confirmation" alone, i.e., merely a binding offer from a credit institution, is sufficient for the work contract to become "valid." Therefore, it does not depend on the conclusion of a credit agreement but only on the obtainability of the financing.
That probably was not meant that way. You surely only wanted to be bound to the work contract if the measure as a whole could be carried out. This then means the possible purchase of the property after the financing approval by the bank.
Now one would certainly have to look at the exact text and any further correspondence if one wanted to interpret the intended contractual content. However, interpretation by the court only takes place if the main contract is not clear in its provisions, which may also have occurred due to differing assumptions (supported by correspondence / emails / witness statements).
If you therefore want (or have to) cancel the effectiveness of the work contract, then quickly go to the lawyer of your trust and see if this can still be prevented.
At first, I would suspect that your revocation of the financing cannot annul the effectiveness of the work contract. Culpa in contrahendo also applies to you, and there was the "Financing Confirmation." Very good other arguments would now have to be brought to the table.