I've re-read your OP and I'm not quite sure what you are seeking but to make clear -
While the baby is in utero, you have no rights.
You can not impose yourself upon the birthing of the baby.
A mother has several weeks to register the birth.
You can not even begin to exert any control over the situation until after the registration of the birth (which you have no right, as such, to attend).
If your name is not applied to the birth cert upon registration (which it can't be unless you are invited by the mother), you could then seek PR by agreement of the mother or through court.
If paternity is in dispute, either side can request confirmation by DNA test, through court if necessary.
Once PR has been established, if not already in place, you could seek a contact agreement and/ through solicitors, mediation or court.
Unless your ex has a change of heart, you are in for a lengthy wait.
I'd suggest you choose not to allow this to affect your bonding with the child and again,
see a solicitor FYI but leave this lady alone. Leave routes of communication open but do not harass her by any means. Her welfare is the welfare of your child.