Do not buy more than you can use, afford or store
Prep according to your budget as you might need to spend the money on something else.
Insulate your house/flat.
Thick curtains
Draught excluders
You should not use a camping stove indoors so plan where to use outside.
Perhaps a Kelly kettle or generic similar kettle. (Fire lighters of vaseline and cotton wool.) (Expensive)
Food you just add hot water to.
(Cous cous, mugshots, cup soup, custard,instant hot chocolate)
Food you can heat easily on a stove or in a microwave (limited electricity)
Barbeque and fuel ( disposable BBQ are quite cheap as a one off emergency)
Food you can eat cold straight from a tin/packet and tastes nice. (Crackers, dried fruit, tinned fruit, evaporated milk, whatever)
Water, drinks, (we have fruit juice and pop) means to filter and purify water. Something to collect it in.
Toilet. Bucket, cat litter carrier bags, porta potty and bags. (Can hold up to 11 stones otherwise aim straight!)
Think of ways to reduce your energy use. (Get up with the light, go to bed with the dark, batch cook and reheat in microwave, insulate, solar power phone charger)
Plan to sleep together all I one room if a power cut and it is very cold. If you have a tent you can use that as well.
Food flasks to keep you meal warm until needed. Also to store hot water from the kettle if the leccy goes off.
Keep some cash for emergencies.
Grow your own veg in summer, microgreens/ salad in winter.
Wind up torches and radio.
Entertainment that doesn't rely on electricity or lots of light.