Hello OldGod. I am sorry to hear it has come to this. I am also glad to hear you have access to SN.
I hope, before going on with it, you have read the resources page, to inform you on the best step-by-step of how to perform this process. Proper fasting, and if possible other medications are a nice plus, but if not they ain't necessary, and really, the discomfort of SN comes only from if you have doubts: that you will only slowly fall sleep. It can cause some discomfort if this wait is a moment of doubt for you, so take this time to sit in silence, and to embrase the decision you are about to take. Then, once you have taken the SN, lie down, and focus on the feeling of your eyes slowly closing, knowing it will soon be over. Don't be afraid of it, embrace it.
Don't worry. Everything will be fine. It will all be over soon. And once it does, the eternity of peace and happiness awaits you.
Once again, I am sorry it has come to this. You will soon find peace.
We all love you and support you. Best of luck.