Welcome to the Bunnings Workshop community @pearsonify. It's great to have you join us, and thank you for sharing your question about how to hang a hammock from the roof.
Would it be possible for you to post a photo of the tent and roof you're planning on hanging it off from? It will give our members a better idea of what you have. They can then offer a recommendation on how to hang the tent. Are you renting or is it your house? I only ask so that we will know if you can drill into the structure of the house.