NOTE: This answer answers the previous question 'What were Gilbert's views on women's education?'. I will try and also answer the new question.
It seems he was very pro-women, there is a lot of evidence to suggest he was a feminist.
From Jane Stedman's biography - W.S. Gilbert: A Classic Victorian and his Theater:
"Gilbert always enjoyed the company of women, particularly intelligent ones, and he was attractive to them,"
He also had three sisters - Jane, Maud and Florence, and was extremely close to them, though his parents were always very distant. He had many female friends, as well as working with several female theater managers, including Marie Litton and Priscilla German Reed, and he took part in amateur dramatics with Marie Wilton.
Furthermore, he asked female novelist Annie Thomas to marry him, showing he thought that a women with this job was totally acceptable, and though she refused they remained friends.
So why are some of his plays based on typical Victorian women, and verging on being sexist?
Well it is likely he did this for the audience. His plays in order to be successful needed to be about that era, and if in all his plays he showed feminist views then the audience wouldn't be so interested or comfortable. Think about how Henrik Ibsen's plays went down with audiences. His play A Doll's House shocked viewers and caused great controversy from the very start when the main character - a woman - walked out on her marriage, children, and life and left men behind, quite the opposite of the Victorian idea for what women should do. Another of his plays Hedda Gabler shocked the victorian audience even more when a married woman takes her own life with a revolver. To avoid such things happening in his own plays, Gilbert couldn't be too open with his personal views.
We still need to remember however, that he was still a Victorian, and from the sources above he'll have been brought up from a young age being taught that woman had a lower place in society than men, as the Victorians thought. He may have been a feminist in some respects, but it is possible that the idea of women being educated was too ridiculous, even for him.
There is no clear evidence anywhere I've looked though, so we can't be sure what he truly thought.