Before you practise insight meditation there are some preparatory stages you should go through. The first the Pali scriptures mention is when one has spoken contemptuously or in jest or malice to or about a noble one - a puggala in Pali - who has attained some state of sanctity or enlightenment in accordance with the teaching of the Buddha. Then he should apologise to the Buddha. He should apologise that noble one, a puggala. If he is not available here, if he is deceased, he should make apology through his meditation teacher. I think you need not do this because you may not have spoken ill of any noble one, a puggala, because you may not met such a person in Australia.
The second stage is that you should entrust yourself to the Lord Buddha who teaches the technique of Vipassana meditation, by interesting yourself in the Buddha you can go through your course happily and peacefully. Though you may have unwholesome or dreadful visions in your meditation you wont fear them because you have entrusted yourself to the Buddha. Also you have to place yourself under the guidance of your meditation teacher so he can frankly instruct you without any hesitancy. If you do not place yourself under the guidance of your teacher he may not be reluctant to instruct you even though you have some defects in your practise.