OK OP, assuming you are genuine:
Most people, when their circumstances allow, have some luxuries; it might be fancy phones, sky subscriptions, eating out a lot, holidays, fancy cars. Or it might be a preference for expensive food and Boden clothes.
You feel like people are sneering at you because of your choice of luxuries but actually I don't think they are. They're just frustrated because you don't see that shopping at Waitrose is a luxury not an essential and that you CAN'T afford it. When the household income decreases below a level where the luxuries are affordable then the luxuries, whatever they are, have to go. Your luxury is boden and waitrose. If it was a fancy sky package and a merc folk would be telling you to downgrade that too.
It might be nice for your kids to wear boden, nicer for you to eat waitrose food, nicer for everything to be fresh not frozen but it's not essential.
Buy a freezer so you can batch cook healthy meals; curries, chillis, stews, soups (things in sauces basically) freeze very well, and you can heat them up on a hob or in the oven so no terrifying microwave required. I'm sure you prefer to eat only organic, free range etc but you CAN'T AFFORD IT. Your children's nutrition and wellbeing will not be significantly compromised (likely not compromised at all) by you buying chicken from Aldi rather than Waitrose.
Clothes; you haven't said how old the kids are I don't think, but they don't need that much. If they're little then supermarket clothes are absolutely fine or you can often get very good deals if you wait til the late stages of the Debenhams sale (70% off) and the quality is good. If they're older then they won't be growing that fast and won't actually need any significant amount of new clothes so don't buy them!