It doesn't have to cost a fortune though.
We eat healthily with minimal UPF (not none, because we are mainly vegan so we do use some vegan milk and meat substitutes though I'm also big on pulses and tofu). We are also on UC so hardly well off!!
I wouldn't buy strawberries out of season, of course they'll cost a fortune! I also don't buy meat. But we always have fruit - it's just seasonal or from the reduced section, or frozen.
For breakfast the DC have stewed fruit (apples with cinnamon, or frozen fruit cooked up into a compote, I batch make a week's worth every Sunday) and some seeds on porridge/yoghurt depending on weather.
We have a rotating meal plan that's always based round soup on a Monday (so we can have it for lunches during the week), pasta on a Tuesday, rice on a Wednesday, jacket potatoes on Thursday, pizza (home made) on Friday, the DC take it in turns to choose what we have on a Saturday so it's often a bit more "treat-y", and a vegan roast with a proper cooked pudding (apple crumble, fruit upside down cake, sticky toffee pudding etc) on a Sunday.
Snacks are Nairn's oatcakes, Aldi mini bread sticks (excellent non UPF crisp-alike), apples, flapjacks, crumpets with nut butter, but tbh a lot of the "I'm hungryyyyy"s are met with "dinner won't be long" because frankly there's nothing wrong with kids feeling hungry in the hour or so before a meal!!