Once I'd run to Marks and Spencer across the road and done a high speed tax of all of their easily carryable and preferably non-perishable goods, I'd come back in here, shut the shutters, shut the door to the back offices and smash the keypad, lock the two inch thick steel doors, come upstairs, dragged the fridge and water coolers through into the stockroom, locked the electronic keypad lock and the two high security bolts on the door, and then settled down. For more water, bathroom facilities and internet access I need only break through to the next three rooms, all of which have door locks, and I could disable the fan in the air con unit for access to the roof, which could be turned back on to prevent any zombies getting down it.

Oh no, I haven't already thought about this at all!