What is your not fully certified, yet? I'm working on my Media Specialist certification. I work at private school so state certification is not stressed.
If you are teaching in a school (private or public), I believe a pay stub and/or a letter from the principal stating that you are teaching would do. However, I would call the S/D to make sure what they require if you don't have a teaching certificate.
I think I will because all my pay stub says is "..... ..... Catholic Church". It's a Catholic school and I don't think I could ask my principal to write a letter so I can get a discount at Disney World. lol
How about a "To Whom It May Concern" letter from the church that says something like "Jane Doe is employeed by XYZ Catholic Church as an Elementary School Teacher" or something to that effect. Just a general letter verifying your employment & position. That way you don't need to tell anyone why you need the letter. The letter combined w/pay stub should do it. But as you said you were going to do: be safe & call & double check with S/D on their specific requirements.
cyn ~ I'm a Catholic School principal and I would be glad to write a letter for any of my teachers to receive the discount should they want it. Although, we are all required to be state certified so we have that document. Why not try and ask your principal?