I have been told that I could now be eligible for a British passport.
Actually no! But from sometime in January .... yes!
A couple of webpages for you to read. Firstly ....
this one ...... which explains the changes. See the page includes :-
A person who has a British mother currently has a right to register as a British citizen under section 4C of the British Nationality Act 1981 if:
he or she was born between 7 February 1961 and 1 January 1983; and
he or she would have become a British citizen if women had been able to pass on citizenship in the same way as men at that time.
The new Act extends the provisions of section 4C to those born before 1961
So having read and understood that .... that you need to wait until the change to the law happens in January .... now read .....
this page ..... which explains about the current provisions, which as you know know will have their date range extended in January .... and then cover you.
Also click the "How to apply under the UKM category" link on the right of that page.