I would encourage you to try your local Gemeinde. I just asked mine (Thalwil) about German courses, and part of the form to register for classes was actually wondering whether or not you'd be bringing children with you (and asking to have their ages identified). I thought that was positive -- namely they were expecting kids and preparing for it. The downside was they only had A levels (i.e. beginning).
While I don't know about their childcare possibilities, the ones I'm currently focusing on (particularly based on reviews on the EF) are
Migros also has language courses, but there aren't that many conveniently located where I am, so sadly those don't work. But you might check their nice English webpage: http://www.klubschule.ch/Services/%7...4DD993669&_z=z