If you donate sperm to a single woman you would be seen in the eyes of the law as the 'child's father'. This means you would have the right to apply for parental responsibility, but may also be financially responsible. The amount of rights you would have depends on several factors, whether there is a legal donor or co-parenting agreement in place, and what level of contact you intend to have with the child. If your intention is to co-parent then it is advisible that you get a legal co-parenting agreement in place drawn up by a fertility law specialist.