I can't see the pictures, but regardless my honest opinion is NO, definitely not. I don't care how quiet the horse is ...she's 3. She's still green. You are not a trainer, you do not have the skill or know-how on training a horse.
Also, if I were the owner of a 3 y/o (or any horse that needed training for that matter), I would never consider a person who had only 1 year of lessons under their belt. No way, no how. If this owner would truly consider that, then that can't say too much about how they value their horse's training.
Please find an older, been there done that type horse who can pack you around while you learn.