If you have a health condition, first things first.
Are there any products which are non prescription that make your life easier?
Start with prepping some of those.
If there are prescription items, make sure you have all your prescriptions filled promptly. Don't put it off for a bit meaning to do it next week because you haven't quite run out yet.
If you need your preps, you don't need to be worrying about those things as well as anything else.
You take care of yourself so you can take care of your family.
Book a slot now if you want a home delivery, even if you think it is a while ahead.
If for some reason you change your mind & don't want it, you can just go in & either cancel it or change it to a delivery slot on a different day.
Two weeks will pass before you know it & then you may only be able to get a slot two weeks after that.
In Tesco, special offers change on Wednesdays.
You can't buy everything at once so break it down into manageable pieces.
Ignore every random gadget you might see mentioned by preppers.
You start with things you need to maintain your health (including food) & your hygiene.
If toiletries are super expensive in your local shop, aim to get those in your order - or plan a trip to town & get them there.
Same with household misc like washing powder, dishwasher stuff, bin bags etc...
Make a list of what you actually use, not what you think you should have in the cupboard, then aim to buy a spare.
Food wise, start by aiming to have 3 days extra food.
Look in your cupboards & see if you have that already - if you couldn't get to any shops could you all eat for 3 days?
If the answer is yes, even if you'd all be living on instant gravy, rice & tinned peas for every meal for those 3 days then frankly you are ahead of a lot of people in this country.
Once you have 3 days sorted, then you can look at extending it out to a week.
At some point you have to decide how long you want preps for.
Are you looking at enough to get you by for an overnight power cut? a week? 14 days isolation? a year?
Pick a time & stick with it.
There is no point buying a ten year supply of rice if you are only trying to prep for 14 days.
Don't bulk buy anything you haven't all tried & liked.
Best way to make your whole family miserable is to sit there offering them Fray Bentos Pies that nobody likes which you bought on special offer on the grounds that if you had nothing else you'd be glad of it.
You won't be glad of it, you'll bitterly regret not buying something you liked when you actually could.
Write down a list of the meals you usually eat in your house.
Are there any that you tend to eat each week?
Meal plan around what you actually like as a family, not what has the longest shelf life.
Then work out your shopping list.
A list is your friend.
That way you can see from your list you have 4 bottles of shampoo & don't need any more right now.
Or that you only have the tube of toothpaste that is in use in the bathroom right now so you definitely need more of that.
It's really easy to accidentally end up with a years supply of something if you don't know for sure what you already have.
Once you get to the point where you have a weeks worth of everything that will not be eaten in the next week, then you start extending what you have just a day or twos worth at a time until you reach your target.