Depends whether I'm at home, or at uni.
If I'm at home, I'd grab my family and dogs, text my mates with my plan, get in the car, drive to the old gunshop in the village centre, (it's not a big area) then drive to the massive high security asylum for the criminally insane that's not a mile away from my house, on top of a hill. Surrounded by forest. Kill the murderers in there, possibly anyone else who gets in my way. Form a semi-dictatorship, not allowing chavs or dicks in there with us. Then have a nice cuppa tea and wait for it to all blow over.
If I'm at uni however, I'm on the outskirts of London and I live on the top floor of a 16 storey tower. With lots of locks. I'd go steal food from other flats (hopefully) and hole up on the top floor. Or maybe raid costcutters if it's clear. Barricade the door. Not let anyone in. Worst comes to worst, go live on the roof and wait for help. Then have a nice cuppa tea and wait for this to all blow over.