Ok,
For anyone else in this situation:
I called legal aid and he said that in the event that you have no idea where the father is and he hasnt had contact with the child for a few years, contact your local court and the local magistrate will probabloy grant you an order to change the name without the fathers signature.
i have to say that would just be ideal. If that doesnt work ill just hyphenate her name, cos im pretty sure he cant do anything about that anyway.
Thanks for your help!!