Birthrights:
Many patients - women and men - feel tired, overwhelmed and vulnerable and would love a DP to stay outside visiting hours, including overnight. In the interests of equality, surely this should then be available to all patients, not just those on post natal wards? Other than your arguments in your document you linked to earlier which were very much about improving the overall birth experience for fathers (this was prominent in that doc, but I notice you are backtracking now), you have not given any reason why post natal patients should be given any special treatment over and above other (equally, but possibly differently, vulnerable) patient groups. And why these needs of post natal women can best be met by untrained family rather than extra/improved hcp support (as is argued in the case of other patient groups). You really need to think about this, and I don't see that you have.
You also need to square how this fits with your broader campaign on dignity, as well as the right for patients to be nursed in a single sex environment, medical need permitting. That the members if the opposite sex who are resident on the ward are not patients is splitting hairs. Why are post natal patients not entitled to this right, when all other patient groups are? You have not advanced an argument for this at all.
Although you have said that you are not motivated by cost-cutting in the NHS, you need to think about the knock on effects such a policy could have, both to the quality/quantity of HCP involvement on post natal wards, and in other areas of care, if this us seen as being a cheap fix to inadequate staffing levels. These concerns are real. I gave family abroad, where nursing care is much reduced and the expectation is that family will provide much of the auxillary, including overnight. It is not a good system. It exhausts patients and family alike. Those who are without family able to provide this care are seriously disadvantaged.
Please do not conduct research into this yourselves! Even if you are qualified in research methods, you have made public your overwhelming bias in favour of this scheme. Such bias is a huge no-no as far as research goes. Better to commission an independent body to undertake it for you, including all aspects - devising the questionnaires, everything.
You should also consider more quantitative aspects such as rates of infection. Keeping infection down is another reason why hospitals try to limit the numbers of extra people on the wards.