I would suggest Karen Mortons group called "Little Poppets" in Ehrendingen. People from ZH come here. The school year starts in August, but you could give her a call to discuss as a new girl did start a few weeks ago.
They teach kids aged 5 to 12 I think. Reading and writing classes. My 5 year old has been going there for just over a year.
karen@littlepoppets.ch