I'd spend those 24hrs with my children... Doing whatever they wanted to do... I would like them to have happy memories of me in the last moments of my life with them... There definitely wouldn't be a bed time that night!
I would quick, write a will. Phone everyone I love and tell them why. I would write a to do list for my spouse who will be immobilized, bag my special stuff and put names on them. Then I would go for a walk in the forest by myself and get ready inside my head. I would rehearse what I would say to my grandmother who I expect is waiting for me. I would take my spouse out for dinner at a posh place and order pheasant-under-glass and the best scotch and talk about everything. Then go to bed hoping for the best.