[tinyteachinthemaking]

Hello Bkduran, and happy Christmas!
I'm currently teaching adults and children (I've no experience teaching the latter).
I've got the Celta that enables you to teach adults. In my opinion, this certificate (along with the TEFL and TESOL), gives you the basics of teaching and allow you to practice in a "safe" environment - I did the semi-intensive course, which lasted about a month and a half, during which I had teaching practices that were assessed by my trainers and colleagues.
It certainly was useful, but it's just a starting point. The best experience is learning by doing and no certificate gives you that.
However, in your case, you could see how it goes without a certificate. Then if you feel you could use some help, there's the CELTYL (an extension of the Celta), which focuses on young learners.
Keep in mind though that it's quite pricey and you will have to invest a lot of time and energy into it.
Hope that was useful. If you have any more questions feel free to contact me.
Emily.