I think that the first thing we need to do is to bring back cookery in schools - where all children can learn the basics of cooking - how to prepare the raw ingredients, what the terms in recipes actually mean (because if you don't know what dice and saute the onions means or how to do it, you aren't going to feel confident about tackling that recipe). They need to be learning how to prepare and cook the food that will nourish them properly - casseroles, bolognese, tomato sauces that can be used for pizza and as the basis for many pasta dishes, burgers made from proper mince, with oven wedges they have made themselves, not out of a packet, curries etc - so they know they can make themselves the food they like and it still be healthy.
It's giving them the basic vocabulary and skills, so that they have the confidence to make their food from scratch, rather than having to rely on packets, ready meals and takeaways.
They also need to learn the basics of good nutrition, and how to build a balanced diet - which they do already, I know, but which is not that useful in the absence of the cooking skills.
And they need to learn how to plan their meals and budget their money, so that they can see how much cheaper it actually is to make your own food rather than buying the ready meals etc.
There needs to be less designing of packaging, and more learning of the real-life skills that the children will need in order to feed themselves properly.