I would be very careful about this. A referral to SS is for if they perceive something concerning. Refusing medical care is a choice and not an issue, but there can be blurred lines with issues like coercive control, isolation of the child, suspicions of drug and alcohol abuse, paranoia in the mother and related mental health issues etc.
Quite often, when a woman presents at a hospital to give birth and no antenatal care has been had, it raises big concerns about why this choice has been made. If you have nothing to fear from SS, you needn’t be worried even if you were referred to them. I was the other day, in fact! Purely for hospital procedure due to an injury my dd had. The nurse wrote on the form she had to refer but didn’t have any actual concerns, it was followed up by a phone call from SS the following day where I explained what happened and they agreed they had no concerns either. It’s unusual to be so concerned about the possibility of a SS referral before your booking appointment unless there are issues a parent knows will be a problem. Many women present with complex issues that have caused the not seeking antecare and that is when a referral occurs.
It is yours and your partners baby. His information is better to have for health reasons for the baby. Refusing to give this for no reason other than concern about how data is handled could be perceived as being unable to put the baby first and your support of that can also be seen as putting your husband above your child. It would raise flags to some about other issues. As an adoptee, I don’t have much birth family history to draw on, but if I did I would certainly give it.
At the moment, it comes across as concerning that you’re making an issue out of a non-issue (very standard procedure that’s easily explained). Lots of people like to say ‘women have given birth for centuries without help’, but the truth of that is they often did have some ‘help’ (not necessarily a doctor) and women still die in countries without access to antenatal and maternity care. It’s absolutely a choice, but it’s best to think of your own limits - in what situation would you seek care? High blood pressure? Lack of foetal movement? Shortness of breath?
I hope you feel able to engage once you get the appointment and can chat to the midwife about why information is asked for. Of course you don’t have to disclose, but remember to think things through carefully and try to go in with an open mind, not a mindset of withholding as much as possible no matter what.