Maternity pay in the uk??

Ladies, what is the maternity pay rate in the uk? I know that I am entitled to 52 weeks off... I also heard that it's usually 6 months full pay and 3 months half pay? I need to know roughly what it is because my manager likes playing a smart one! She did initially tell me that I wasn't entitled to maternity pay because I am zero contract hours but I went to citizen advise borough and was told that regardless of zero contract hours, I am entitled to maternity pay because I have worked with my employer for 3 years and with the same working hours every week... I told my manager and she said "oh, really, my bad".