NSW, Australian here.
I just want to first off declare that going out should be quick, quiet and overall a moment of peace and relief. Hanging, drowning, poison, lacerations and such will not provide this. Especially if your instincts kick in and make you regret your decision after you've made the jump.
However the goal shouldn't be end the suffering, it should be to fuck it off. Unfortunately living is a curse, we're aware of our eventual end, unaware of our purpose and constantly confronted with hardship.
But fortunately there's always something that comes along and makes shit feel ok for a moment. You might eventually realise that there's a whole lot more than what you see as of now.
Like others said, you shouldn't jump to the guillotine and just wing it. The last thing you need to is to watch those who love you, go through the trauma and proceed to do everything they possibly can to keep you after you get out of hospital. Let alone going to the psych ward, that's traumatic on its own. Grabbing a kitchen knife and having at it will only lead to a slow and agonizing death, especially if you regret it. Hanging will only shoot an extreme amount of pain in your head, eyes and ears as it builds with pressure. Drowning, well if you bond your arms and legs together and toss yourself in a bath. Definitely going to be an experience.
Wait it out. Give yourself some time. Personally I find it really nice to just throw myself into a trance of disassociated carelessness. Sewerslvt and m83 are my favourite artists to do this with.
Oh well, that's my 2 cents worth. I was meant to post this last night but I passed out. If you haven't frantically tried to shiv yourself already than I hope you've leveled out your emotions and your desperation has trickled down.