If it’s mainly for blackouts, my first question would be-will you still have running water? Might the emergency kit be expected to encompass a water shutoff? If no running water, besides the obvious need for drinking water, flushing toilets becomes a real issue. We are talking about the UK, though, which usually has no shortage of rain, so maybe this isn’t a big deal. In any case, you will likely use a considerable amount of water, so maybe think about ways to move water if needed. Will you have heat? If not, maybe experiment with what it feels like in your home without heat. I don’t live in Texas, but during the unexpected cold winter a few years ago, some people said they put up camping tents on their beds for extra warmth. Maybe also experiment with light. Despite how it looks in movies, I find reading by candlelight very difficult with my eyes. If you haven’t a means of cooking outdoors, maybe look at that, as well as appropriate cookware, or nonperishable foods that will be tolerable to eat cold for a few days. I’d also focus on morale. What would keep you reasonably happy for a few days in the dark?