Lol they're great aren't they, I love going to the supermarket with a basket full of kale and brocoli looking smug and healthful, no-one needs to know it's for my rodents 
Meal planning doesn't need to be over-complicated, people get into trying to make a magic MN chicken last a family for a week etc, but at it's most simple level, all you need to do to make a meal plan for a week is write down 7 meals (or 3 or 4 if you want to start with half a week at time) you know the family will eat, then the ingredients you need to make those meals. So it could go, spag bol, chilli, curry, stir fry. You need mince, onion, tomato, herbs, pasta for the spa bol, mince, onion, tomato, beans, rice for the chilli and so on. Then once you have the list review it against what you already have on your shelves and in the fridge/freezer. Anything you don't have in stock goes on your shopping list (and you stick very strictly to the list when shopping - don't be distracted by bargains or things you fancy).
The only slight complexity can be looking at the use by dates on meat as if you are trying to do a week's meals from one shop, some of the meat may expire - but I just stick anything that will go out of date before I use it straight in the freezer, and set a reminder to self on my phone or calendar to remember to de-frost in time for the meal.
Once you are into the flow of it you can get into trying to find synergies between meals to make savings e.g. you can buy a whole chicken to go for a number of meals rather than buying pieces of chicken, or big packs of root veg to split between a number of meals or batch cooking and freezing portions for later - but really what matters is that you buy everything you need to avoid having to 'top-up' (as I find this is where the impulse spending creeps in) and don't buy things you won't use!