It's worth getting in some supplies of the things you use the most, which don't need refrigeration, and can be stored for a long time. Keep them in a cool, preferably dark place. I'd recommend the following:
Dried pulses and beans: red lentils are the quickest to cook. Keep a stock of dried red lentils for soups, dhals and adding to stews. Dried beans, chickpeas and other lentils are useful, but take a long time to cook unless you have a pressure cooker. To save your home energy, best to keep tins of these in store as well. Also worth storing: rice, millet (very nutritious, and much quicker to cook than rice; around ten minutes), green lentils, bulgur wheat, cous cous, noodles, pasta, split green peas, roasted buckwheat, wheat/spelt grains (for grinding/sprouting), sunflower seeds, sesame seeds, pumpkin seeds, various nuts, dried fruit, dried milk, muesli/breakfast cereal, porridge oats, flour, baking powder, dried yeast, honey, peanut butter, black peppercorns, turmeric and any herbs and spices you use regularly. And don't forget any pets: keep supplies of non-perishable food for them too.
Fruit and Vegetables
Potatoes should be kept in a hessian sack or thick brown paper sack/bag in a cool, dark place. Check regularly and remove any which are rotting. Sprouts can be rubbed off: the spuds will still be edible.
Onions and garlic store well at room temperature. Too cool, and they sprout. The green sprouts can be eaten.
'Winter' squashes store well in a cool place, usually till late January.
Some apple varieties will keep till Christmas in a cool, darkish place. Check regularly.
Carrots, beetroot and parsnips are best kept in the ground where they are growing, or in a cool, dark place.
Dried fruit is best for storing. Peeled, cored and thinly sliced pieces of apple can be dried on a horizontal cane or string in front of/above a wood burning stove or Raeburn.
Tins and miscellaneous
Depends on what you like to eat. Basic recommendations: tomatoes, baked beans, beans and pulses as above, sardines, tuna, anchovies (for flavour), soups, apricots, peaches, pineapple in juice.
Also tomato puree, bouillon/stock powder, Vecon, Natex (both from wholefood stores) or marmite/Bovril, vegetable oil, cider vinegar, spices and dried herbs. Chocolate, and anything else you like is useful too, and sugar for preserving. Alcohol isn't great in times of stress, when you want to stay as fit and healthy as possible, especially as it makes you less vigilant.
Store some 5litre plastic containers of water (Sainsbury's are the sturdiest), and 1 litre glass bottles of water (Waitrose has these at £1.00 a throw, but you can reuse the glass bottles safely, unlike plastic ones). It may be worth keeping empty screw top glass bottles and jars to use for water storing in an emergency, and a couple of large camping water containers too. Water containers can be safely cleaned with Steradent tablets.
In an emergency, you can use water from a toilet cistern (not the pan!) for washing, etc. If you know there's going to be a water supply cut-off, fill a bath to store fresh water (make sure the plug fits well), and use buckets, bowls and any spare containers. Rainwater from a water butt may be full of toxins from chemtrails, etc. (isn't everything?), but can be used for washing or put through a filter for boiling and drinking/cooking.
British Berkefeld made by Doulton do a good freestanding stainless steel filter, for which you need to buy a pair of 'Super Sterasyl' filter 'candles' at around £40 a pair at least once every year for moderate use. See Doulton.com Fluoride filter candles are also available, at c £70.00…You can also buy more expensive whole house filters and small inexpensive jug filters from healthy-house.co.uk It may also be worth getting a portable camper/walker's backpack water filter bottle for real emergencies.
Toothpaste, spare toothbrushes, soap, soap powder/liquid, any medicines you use, bleach, over the counter pain killers, first aid kit, matches, candles/nightlights, batteries, loo rolls.
In an emergency, think how you will keep warm. Make sure you have plenty of warm clothing, heating fuels, blankets and hot water bottles. A general rule of thumb in prepper planning is to try and source all your household inputs from as many different sources as possible, so if one or two go down, you've still got something left i.e. fire/wood stove, gas, electrics, solar for heating; calor/bottled gas for cooking
Useful prepper items
Small, portable calor or propane gas stove: be aware that for these you'll also need a supply of non-renewable canisters, and once these have gone, they'll be gone, as everyone else will be after them too. Larger, two ring camping gas stoves are better, as you can (hopefully) buy larger, refillable gas canisters for these. Kelly kettles are great if you can operate them safely outdoors, using a handful of dry sticks and pinecones. Best for boiling water, though you can get a small 'cooking' adaptor for them. Small stainless steel pans for use with all emergency cooking appliances are good too. And in a real emergency, you can cook over an outdoor fire.
Torches, batteries, bicycle (and spares/repair kit), good walking boots and outdoor/waterproof clothing, wind up or battery operated radio (emergency use only, to get information if you can see through the propaganda!), non- mains powered phone, mobile phone and charger/solar charger.