Only parents, carers with 'parental responsibility' or who expect to get 'parental responsibility', and fathers who are registered on a child’s birth certificate are entitled to take parental leave for a child. Natural mothers and married fathers automatically have parental responsibility. Unmarried fathers will have 'parental responsibility' if they have been granted it by the mother or have a court order granting it.
If your employer is disputing your right to take leave on this ground, you should contact your union rep. If you are not a member of a union you may want to get advice from a lawyer specialising in this field. You can contact your local Citizens Advice, Law Centre or the Law Society for details of how to get advice and support.