More than 300,000 calories for less than £200
A couple of people have asked, so here is a screenshot of my spreadsheet.
I buy this every year in November and donate the majority of last year's to a food bank in December, the rest goes in my cupboards.
This is an emergency supply for a family of 4 for a month. I generally cook and eat the one pot stuff, every day for lunch (batch cooked and frozen). There is no meat and basic calories. I know my family will eat this and the general idea comes from once holidaying in Cuba (many years ago), where they eat the same dish many different ways and can change it with whatever they can get hold of (add an egg, you can make pasta, add meat, you have stew).
If you decide to have a go, you have to learn to cook this stuff. The flat breads and calzone are an art but everything else is pretty simple.
I camp once a month all year round and prefer cooking on fire than my trangia (more room to manoeuvre).
Water wise I have a lifesaver jerry can that's sat in the loft, it's my biggest outlay but the forces use it, it can do many thousand liters, it's a purifier and it's about £35 a year insurance policy.
My weapons of choice when cooking are mostly a Chapatti pan and a zebra billy can with grill for oven.
I also have a trangia multi fuel stove and the kit that goes with it. Ultimately you don't need most of it and can just use cheap IKEA stuff. For cooking for the whole family I will just use a stock pot.
Generally every day we rotate our kitchen, I bulk buy almost everything but we eat better meals than our emergency supply. I could probably do another month on that alone.