I carry around so much crap in my daily bag that like Habib, I would probably be able to live out of my bag for at least 24 hours! 
Bottle of water, packets of nuts and chocolate, an apple, a utility tool, SAFETY PINS, pens and paper, a packet of paracetamol, various emollients, a book and most importantly my knitting. I suppose I could attempt to stab an enemy agent with my 2mm DPNs.
But in all seriousness, I do think a lot about being prepared. We used to have a 'Brexit box' in the study/lumber room, back in the days when I thought we might run out of nice vegetables so would have to resort to tinned ratatouille, etc 😂and always had lots of tins, dried goods etc. Most of that has been used, disposed of or is out of date, because I'm a very bad prepper and don't cycle my goods. Our main food issue is our younger DC, who is severely autistic/LDs and won't eat anything he's not already sanctioned (no, not even if he's hungry). His diet would anyway make the angels weep but we'd go through all those rice cakes, crisps etc very quickly and with none of the 3 or 4 fresh food items he has, we'd be buggered. He would also be impossible to contain in one room so I honestly don't know what we'd do. And I'm sure anyone else with a family member who has LDs would feel the same.
Sometimes I think - but we're screwed anyway, we don't actually HAVE an indoors, downstairs room without windows! The best we could do would be to shore up the door to the study, the front door, the door to the living room and the door to the kitchen, and then try to exist in the hall, assuming the front door hadn't been blown off. Four of us, two cats, in a really small space. Whenever I think about this sort of scenario I get intrusive thoughts, mental images really, from When the Wind Blows. All those bottles of water fallen over. 
And I don't really have a safe means of cooking indoors if the gas and leccy go off, unless it's safe to move to the living room where I suppose we could risk carbon monoxide poisoning and use the wood burner. I used to use gas cartridge stoves when camping but one blew up on me and I got rid of them! Now I have one very elderly Camping Gaz thing that would still produce carbon monoxide, and a rocket stove which is great - if you're outside.
We used to have about 12 plastic bottles of water in the porch until DS2 opened all the caps on them, rendering them useless apart from flushing the loo, and we got rid because they kept falling over. Seriously, do many people have that much room to store enough water for their household? Plastic bottles are no good for long-term storage anyway, I think the limit is 6 months?