I havent read the rest of the thread yet and another poster has already set out to some degree the process but there is a clear lack of understanding of the threshold and court processes for a situation like this
The first step is that the LA has a duty to contact both sides of the family to determine whether any birth family members are willing to present for the child and then be assessed. No court would allow for proceedings where that wasnt happening.
Whether a father has PR or is on a birth certificate at that stage is irrelevant, if it came to a father who had previously opted out (and there are many of those) being assessed, putting his family forward, then the court will ensure that he is given PR if necessary for the child. This doesnt always happen but the court will direct this, whether the mother wants this or not
Later once all assessments are done, IF, no family members are found to be capable or willing to care for the child, then a decision is made to seek permission to proceed with adoption. The evidence needed for why a child needs to be adopted is extremely detailed, stringent, there can be no gaps at all which is why everything and everyone is explored.
The parents would get to meet the adopters if they wish and this is often reassuring. But it could be anyone, from anywhere, single, couples, whoever
In terms of family assessments, then these will be prioritised, the law expects that children are placed within birth family were safe to do so, it needs to be 'good enough' to enable that to happen.