As this is a shared ownership mortgage, you do not have the same choice of lenders as on the open market; however, it shouldn’t make a difference to this issue.
Which HA is this with? It might be good to make them aware, as you will not be the only person this is happening to, and the HA may want to know about it.
From Peabody’s website:
Source of deposit
You will need to evidence your deposit to the mortgage lender by providing a statement showing the source. Where money has been built up in your current account, three months bank statements should be sufficient. However, where money has been transferred to your bank account from a separate source e.g. an investment, you will need to provide evidence of the original source.
It is now very common for buyers to receive gifts from family to help with their home purchase. Most lenders will accept gifts but will insist on the source being verified. Some sponsor’s may be uncomfortable with disclosing their personal and financial information, so it’s important that you discuss this with them in advance.
Sponsor's will be required to:
• Sign a letter stating that the gift is unconditional, not repayable and does not entitle them to any interest in the property.
• Proof of ID e.g. certified copy passport or driving license (photo version)
• Proof of address e.g. certified copy of a utility bill/bank statement
• Evidence the source e.g. 3 three months bank statements (or certified copies)
Please note that gifts from overseas may be subject to a higher level of scrutiny and in some situations may not be accepted - but please speak to your mortgage advisor who can advise on an individual case basis.
Does your dad live in the UK, OP? Was his ID etc requested?