Alrighty then.
Initially it'd take me a while to realise eveyone is gone, say about 3 days.
When I do realise, I will cheer, finally being free from all responsibilities and people.
I would then spend several days stocking up on supplies, generators, food, water, petrol.
Freeze all perishable foods that I will really want later.
Once I'm all set up at home, with other people's stuff, I would start to venture out, specifically to get that one motorbike I really want from Newcastle.
After I got that I would venture out even more to loot more people's places, searching for some place to settle down for good.
After finding the apropriate mansion I would move all my stuff in there (including my dog).
Spend the rest of my days looting, watching DVD's, playing games, destroying shit, reading books, basically having any fun I can.
When I get too old to sustain myself anymore, go steal all the morphine I can find, and take it all at once while on the edge of a really tall building, then when the morphine starts to kick in, shoot myself in the head with a shotgun in a manner that will mean that I will fall off the building.
Better safe than sorry.