Preschool teachers should be graded if they want to teach piano. If you work hard, it is no problem to reach Grade 8 in two years. If you just need to be able to play, it will take about half a year.

Piano teaching is one-on-one, so you can't go to large classes. Of course, the cost will be higher, because there is no fixed difference between regions and teachers' grades. Generally speaking, 50 an hour is very good. The general piano training is one hour once a week. I hope it helps you.