We used an unknown donor, so obviously I disagree with most of the above comments.

All I have to say is that the agreement MUST be mutual. You just CANNOT lead a man along to think he is going to be a father and then decide you don't want him in the child's life as a father.
In our case, we used an unknown donor who had willing donated sperm knowing that he will not have access or acknowledgement as a 'father' to any child that is created of his sperm. We don't know him. Never met him. Don't know his name. He doesn't know us, never met us etc. That was fine as this is what we wanted, and obviously what wh wanted or he wouldn't have become an unknown donor.

So if he wants to be a part of this child's life, you either have to accept that, or use an unknown donor. It's just not fair if he donates on the understanding that he is going to be a father, and you change the deal and decide he is nothing more than a sperm donor, or 'godfather'. In fact, in that scenario, I'd expect him to take you to court for access or custody.