I've started looking into it, via the National Donation Gamete Trust. So, getting a rough idea of what's involved.
I've always said I only wanted one child myself, and don't think this is likely to change.
My views on what makes a parent are slightly more distorted, perhaps of the fact I was adopted. To me, parenthood is not about the genetics, but about who cares for that child, who raises the child and provides the love it needs (sorry if that offends anyone, but I hope my logic is understandable)
I have no experience of this at all but just wanted to say what a lovely thing you are doing. There is a great shortage of donor eggs and if I ever manage to have children myself, I would certainly like to donate as well.