I hope you reconsider this. This sounds like an excruciating way to die, and I hate to think of someone who has already suffered in life dying in so much pain.
If you survive - which is far more likely if you do this in a public space with the authorities searching for you - the aftermath will be awful. Permanent pain and damage, surgeries, skin grafts, risk of organ failure, amputation, sepsis, severely disfiguring scars...
You do not deserve to endure such agony, and sadly I doubt that doing so will truly change the mental health system or raise sufficient awareness. Inadequate healthcare and suicide is a recurring theme. Some speak out and most of these individuals fade into obscurity despite their best efforts unfortunately. The media isn't going to keep a subject in the limelight that is uncomfortable to hear, and it's even less likely that they will understand and showcase your plight.
Society is more interested in silencing suicidal people - out of sight, out of mind - than actually improving quality of life or pioneering genuine reform.
I would hate for you to suffer so unbearably, only for your story to be buried and forgotten soon after. You deserve to be heard and understood, but unfortunately I don't think setting yourself on fire is going to result in that when we live in a society that perpetually fails to listen.
If you are still here, please please reconsider. You deserve so much better than to endure such torture, whether that's in life or in death.