Milton sterilizing tablets, th en you just need a bucket or tupperware box big enough. Fill with water in the morning, drop in a tablet and its good for 24 hrs, bottles need to be in for 30 mins to sterilise and dont need rinsing after.
Babies - next size clothes as they get through sizes quick, same for nappies.
For brexit i dont think water will be an issue but i would have a couple of tins of formula to hand in case of supply issues, same for any essentials like dummies, calpol that could end up stuck on a lorry in calais when you need them.
If you have the funds now, having a stock of the expensive stuff.like formula and nappies wou ld help.if there are price hikes because of import fees/supply problems.
Older kids, next season clothes, treat foods, a supply of staple foods you know they will eat with minimal complaint and thats nutritios/filling.
- Short grain rice for risotto or rice pudding
- UHT milk or milk powder which works for cooking
- Pasta and sauce
- Soup
- Baking ingredients including cake stuff. The sachets of cake in a mug mix are often discounted, quick, easy, just need milk and satisfy the need foe a hot pudding. Flatbreads are easy to make too.
Suitable multi vitamins for all and basic first aid kit is always useful.