@Twoleftuggs
What do you normally eat in a day? What does your normal weekly shop look like? Do you cook from scratch or is it more ready meals etc?
For us, I batch cook a lot of stuff like pasta, or vegetarian chilli, or chickpea curries and we also make our own bread and chapatis so have a lot of bread flour in regular use.
And this is all mostly stuff that keeps, barring the fresh veg, so I'm pretty sure that I'll be able to keep meals fairly 'normal'.
DH eats a lot of instant noodles, so we have those in. Our 'treat' food is homemade pancakes, but I'm vegan so I make them with soya milk and non dairy spread, both of which keep forever along with flour/baking powder/sugar /vanilla extract etc.
The freezer has stuff like meat and pizza (DH and DD aren't vegan) and frozen veg. We also also have porridge and cereal bars, which I eat a lot of anyway.
I think the key thing here is that we've just bought extra of stuff that we normally eat, as long as it can be frozen or has a long expiry date and won't be wasted. The best thing to do I think is look at your weekly shop and work it out from there.
You definitely don't have to go overboard, for us it's literally just having a well stocked freezer and some cupboard space set aside for extra tinned things, pasta and rice for basic meals that we will eat and enjoy anyway, as well as a few extra packs of paracetamol, calpol and nappies and loo roll, all stuff that we'd use over the longer term anyway.
And that's really it, we're not kitting out a nuclear bunker but just feel a bit better knowing that if we suddenly couldn't get out for whatever reason or if supermarkets became a nightmare then I would still be able to feed my family things that they're used to and enjoy.