How much variety do you need? I mean, are you the kind of person who likes to eat a different meal every day for a month at least? Or the kind who has some regulars but likes to introduce new ideas once a week?
by meal planning, and keeping a rough record of what we've had, I've slowly built up a really large reportoire of meals. so we have a few that are on regular rotation (forever or for a few months), a few that come out now and again when I remember them and then a few get added as new ones when I discover them. I'm also fairly good at doing the same meal as a base, but varying it a little - eg we quite like a steak sandwich/flatbread, but we'll have in slightly different forms, with different accompaniments this week to what we'll have in 2 weeks time.
Overall, meal planning helps to keep costs down as you only buy what you need AND you use it all becuase it's all planned out. I also regularly have something like a fried rice or stir fry type meal planned for the end of the week as a way to use up the ends of whatever veg etc have been left after all my other meals.
LImit meat or choose meals that are low meat - eg our steak sandwiches above are still a treat, but it's a treat we can justify in a way that a full steak per person we can't from a cost perspetive. We often do things like a pasta sauce with no meat or very little meat - eg a tomato based sauce with veg with half a chorizo ring to add flavour and "meatiness" at very little cost.
When things are very tight, I like to plan at least one or two v v cheap meals per week - something like pimped up baked beans on jacket potatoes or a very basic tomato pasta sauce.
Having said all that, one thing that I have noticed with my shopping is that my dinner meals is, at most, about 1/4 of the total cost every week. So that's something I'm working on keeping an eye on - swapping to cheaper supermarkets for lots of fruit and veg, reducing the use of expensive cereals, shopping for deals on petfood (hello Amazon), limiting snacks etc etc.