Veggie recipes are the way to go to save money and healthy too! I love a chickpea curry, like this one:
www.jamieoliver.com/recipes/vegetables-recipes/sweet-potato-chickpea-amp-spinach-curry/
Jack Monroe's kidney bean burgers are often recommended on here and usually go down well with kids although I find them a bit crumbly myself and prefer this Riverford receipe for courgette fritters/burgers which is similar but holds together better IMO - I often do it with carrots instead of courgette or a 50/50 mix. Both recipes here:
cookingonabootstrap.com/2015/01/31/carrot-cumin-kidney-bean-burger-9p/
www.riverford.co.uk/hen/recipes/view/recipe/courgette-fritters-with-feta
Other ideas, a nice hearty veg soup (again use up any bits of leftover veg), makes a good dinner with (hot) crusty bread with leftovers for lunch. Add some lentils for protein/bulk.
An easy pasta bake made with tinned tomatos cooked up for a while with herbs, garlic and onion, any pasta you have in the cupboard cooked through, then all thrown together and top with cheese, cook through in the oven. Great as it's mainly store cupboard ingredients although a bit lacking in protein!
Shakshuka: www.bbc.com/food/recipes/shakshouka_74716
If you want to keep eating some meat, sausages are not the healthiest but cheap and go a long way. Chop them up and/or squeeze out the meat and serve as 'meatballs' with pasta or in a stew, like in this receipe:
www.redonline.co.uk/food/recipes/a500232/jools-oliver-s-pregnant-pasta/
When all else fails beans on toast is actually quite a nutritious and filling meal - I sometimes vary it up by making curry beans (add curry powder before cooking), BBQ beans (add ready made BBQ sauce after heating the beans) or cheesy beans (melt some cheese over the top of the assembled beans on toast!).