Unfortunately pretty much anything prepackaged will be too high in something - fat, sugar, salt or all three. Kids can tolerate about half as much salt as adults. From memory the recommendation is around 600mg for 8 and over and around 300mg for under that. Which if you check the labels of everything you buy is next to impossible. A vegemite or cheese sandwich would probably get you there on it's own (add the bread, butter, and filling).

For snacks, there are quick and easy things you can do though without packaged foods. Fruit, unsalted nuts (if there are no allergies), rice cakes (the Coles or Sunrice thick rice cakes have next to no salt, but most are too high in salt), sultanas, natural yoghurt, baked pita bread with hommus dip (homemade if possible or even with pureed vegetables instead).

For meals, you can still also do fairly quick and easy things. Tacos are a hit with my boys - I make the taco seasoning myself (chill powder, cumin, paprika and garlic granules or crushed garlic) and buy the lowest fat and lowest sodium tortillas or taco shells. Spaghetti bolognaise with the low sodium tinned tomatoes works well (there is only one brand I can find lately that is really low, it's Italian, let me know if you want the full name) - you can put any veggies in a bolognaise, usually I manage at least 5 or 6 different ones. My DH makes the best curries from scratch (not using jars) but this takes a bit longer. Salmon patties, grilled fish with salad, cajun chicken salad, home made chicken nuggets with pureed cauliflower in the crumbs are some more ideas.