My friend went through informed consent after getting nowhere with several therapists, and I'll be going to the same place and doing the same thing.
It doesn't really have anything to do with parents or anything. Basically, they are going to give you a physical and go over your medical history and psychological history, etc. Based on that, they tell you all the risks you will have by going on hormones (they missed something with my friend, she had a stroke because of a hole in her heart that no one was aware of).
The informed consent is just saying you're aware of all the risks and you still wish to proceed with taking hormones. It's not illegal, though to most psychologists it is frowned upon, and a way to "bypass" therapy (aka read as "self-diagnosing"). So, in a way, it is saying that you feel your are competent enough to decide to take the hormones on your own, and not have someone tell you it's a good or bad idea. It also, as I've heard, tends to be cheaper. But be careful, because my friend was "rushed" on her doses (they increased them very rapidly). I will be taking it slow for my increases, as I can't afford something happening because of a rapid increase in hormones.
Hope that helps!