You'll be fine. You can always do it with the understanding its a trial run. My sons teacher (who had been teaching for over 30 years) always took new students with that preamble to the contract. & yes you need a contract, church lady or not.

My poor son though was let go as he could not read any notes, but by his 3rd lesson was playing what 10 years students where learning - my son plays by ear & its really hard to find a teacher that is willing to teach that. Oh well Baseball is is live now anyways LOL