I know that you two are really heavily focused on gear, but I think something like having a solid stock of mason jars (various sizes) to fill with preserves would be a far better option then your plastic air tight sealing bags that will quickly run out in most situations. Why not just use ziplock bags if you must? For that matter, you’d probably want to have a big pot and a few key tools to cook your preserving in.
And not everyone is rational. The prepping movement contains overzealous elements, particularly in the US, where natural disasters are bigger and badder and, well, the guns. But those signed up to the movement in the UK are like you and me: relatively normal, with the odd quirk. They just keep a half-tank of petrol in the car at all times, and at least a month’s worth of food, and an alternative way to heat their homes in winter if the gas goes down.
After 9/11, my dad filled a duffel bag with some energy bars, a couple gallons of water, some penicillin, and a map. Amid scaremongering headlines about imminent anthrax and “dirty bomb” attacks in the city, he wanted to have some supplies on hand in case we needed to get out of Brooklyn fast. Were he to assemble such a bag today, he’d likely stumble on a number of companies promising a more wholesale brand of disaster preparedness: a box full of shelf-stable freeze-dried meals, to be revived from their dessicated state with the addition of boiled water.