Hey there akalex...

Are you able to find results for this ride somewhere?

If you search for the results online, or ring the organisers, you might be able to find a range of times that people have completed this in.
Then look for a name you know, or otherwise find the results for women your age...

It is hard to give your a time to aim for, or an average speed to ride to without any knowledge of the course.

Good luck