@Allthesocksintheworld
You may have more space than you think, as in you probably have to be well organised and think ahead and probably have got a lot of stuff already for the more likely, less end of the world stuff... which you probably could not do much about anyway.
EG: a well stocked medicine cabinet and decent first aid kit.
between you you probably have spare chargers, and more than one phone possibly on different networks.
DIY tools to mend stuff.
some preps are tiny and cheapish: eg water purifying tablets
some preps are knowledge/skills based.
some preps are relationship based, building a support network with friends neighbours, knowing who you can trust and who you can trade skills and resources with. (having a live in bloke who I hope would be useful/practrical/emotional support )
what are the likely issues you could have?
house/shop fire, flooding? (from below and above, such as leaks in roof and pipes) illness, covid isolation. (if you are feeling shit you are not going to want to go to the chemist for paracetamol.) weather and climate: such as heat waves keeping cool and keeping warm in winter, price rises, supply chain disruption industrial action, (extra bin bags in case the bin workers go on strike?) accident