Metastatic Mess: Self employed, no super, life or income protection, expired health insurance

You're not silly at all - pretty much doing what people our age are doing all over the place.  We don't expect a diagnosis like this and no-one understands the cost of cancer until they're in it.  Everyone just assumes that it's taken care of.  I do hope that you can access some financial assistance.  If you haven't spoken to your medical team about your financial situation, please do so as they will often come to the party where possible.