One of my Dc's favourite quick meals is spinach and ricotta ravioli (any brand) or tortellini mixed with tomato sauce some cheese on top and baked in the oven until hot, served with supermarket garlic bread and some broccoli and peas.
I think pasta bakes are usually popular
Homemade pizzas (you can buy frozen dough for the bases if you don't have time for that bit)
Fake "roasts". I do up some Paxo which they love, roasted portobello mushrooms, lots of veg, roast potatoes or celeriac mash, I make a gravy with the juices from the mushrooms a bit of cornflour, a bit of a veg stock cube and a drizzle of soy.
You can get tins of lentils for around 50p and they are great to use instead of mince, fantastic for shepherd's pie. Tinned blackbeans make great chilli.
Vegetable pasties (use bought shortcrust to save time) with potatoes, celeriac, carrots, peas etc work well. If you like spice you can add some curry powder to spice them up.
Vegetable stir frys with noodles are quick and tasty.
Vegetable kebabs with couscous, pearl couscous or quinoa work well. I alternate courgette and mushrooms serve with green veg and make a nice honey, lemon, oil dressing with some harissa and yoghurt on the side for those that like it.
Hello fresh have lots of easy vegetarian recipes here:
www.hellofresh.co.uk/recipes/veggie-collection
You don't need to buy their boxes, just get the ingredients in your usual shop.