Misfire - it seems that you possess the necessary basic requirement -- the desire to teach. If you have the desire then the rest will fall into place. Do not focus on "not being good enough."

Focus on the new world you will be introducing those children to. Focus on the possibility that one of those children may become a scientist because of something you said or introduced them to.

Think of what the outcome could be if you do not do this.

You will never know if being an outdoor educator would have been fulfillng. You will never know if you would have made a difference in a child's life.