I don't know if you care about this, but you should also know that as soon as you take money for teaching lessons, training horses, riding, etc, you are no longer able to show as an amateur. My boss/instructor used to do a lot of showing, but part of the reason she stopped is because when she started teaching she would have had to start showing as a professional and she didn't want to do that. I also work with a girl who has refused multiple offers to ride other people's horses for money because she wants to keep her amateur status. Again, not sure if this applies to you. Just something to think about.
The other option is what I do; assist a certified instructor with their lessons in order to learn and see if you actually enjoy it. Because there is a huge
difference between horse experience and kid experience. I had both when I started helping with lessons, and it still took me months to get to a point where I was trusted to do a lesson by myself. I also have friends who help with the lessons (it's a thing everyone does at my barn) who hate it. It's really not for everyone.
That being said, if you do decide to go forward with this, good luck! Teaching (especially with horses!) is one of the most rewarding things I have ever experienced.