Nicki I earn twice what my husband does, and he still thinks he has the most important job. I know exactly how you feel, we have had tense argument about childcare, granted mine stayed at home for am extra two month so I could go back to work because we needed the money, now we are both back full time and nursery fees are a killer.
What about a childminder just post school, sometimes they do into the early evening so you could do your zumba class.
I know how frustrating it is, hang in there, there is always a solution.