My ex partner and I separated when our daughter was 7 months old, we agreed to change her name to mine on her birth certificate as he was to play no part in her upbringing and agreed she should no longer have his name. He has now, seven months later decided he wants to have access, does this effect his rights?

Unless there was a Termination of Rights through the court, he still has rights to his daughter.

Of course he has rights, he is the father. He may have to go to court to enforce those rights, but only a court can take his rights away.