I’ll caveat all this with if financially possible.
Stock up on easy foods; little cheese, yoghurts, crackers. Make sure they are on shelves the kids can reach.
Buy some small bottles of water. Again put them somewhere easy to reach for the kids. A mini squash too if your kids won’t drink water. It’ll be easier for the, to distil.
Stock up on 4/5 days for you all on para and ibu. I was always amazed how quickly the liquid calpol used to run down. Put a note pad and pen with them so you can write down when everyone has a dose of something. It’s so easy to get confused when you’ve more than one to deal with and/or you are ill yourself.
Get some anti bac and soap/stock of clean towels in bathroom.
Keep chargers to hand for tablet, laptops, phones etc so there is easy screen time for them.
Keep some changes of light clothes and underwear nearby where we you set up camp.
Keep some bin bags nearby too so tissues can be thrown away after each use and not left handing about on the arm of the sofa etc.
If you don’t have online shopping set up, do so now so you can more easily get things.
Similarly with delivreoo/uber eats etc.
Make sure your kids know now how to unlock your front door if needed. Also make sure they know your address. It’s unlikely that they will need it but it’s useful anyway.
If you’ve a trusted neighbour give them a key now and make sure you’ve exchanged tel numbers with them. If no neighbour, a trusted school mum or dad.