Most Yoga teacher certification courses offer some tutoring, or contact, with a mentor. This form of contact is possible, regardless of whether you have chosen an on-site or correspondence-based Yoga certification course. It seems impossible to believe that an in-person training would not have tutoring for interns - but it does happen.
One more point to consider: Does the certifying institution focus on creating Yoga courses or do they also have diplomas for gun smiths, dog grooming, computer programming, and appliance repair? You should consider a school that exclusively educates Yoga teachers.