Mondays we have pssta. Mostly with either bacon or tuna.
Thuesdays is casserole or curry time. Mostly with either pork pieces (small or big) or chicken. Rarely beaf chunks. Only if we have that in store.
Wednesdays, Thursdays and Fridays are inspiration days. I don't really plan, just see what's in the cupboard and make it. If I have no idea, I look on the internet for something (sometimes I come up with really surprising results). But I always have bought five/six kinds of meat and two packets of bacon, so we can choose what to eat. And LOADS of vegies.
In order to keep my food bill down (we don't really mind, but we try to keep supermarket bills at about 200 euros a month in order to still have enough money to spend nice weekends with a dinner or lunch out), I rarely buy things over 1 euro. Vegies all below one euro. Bags of pasta below 50 cents most likely. Rice, a little higher, but certainly below 1 euro per half kilo. Tuna costs a little more per tin, but not more than 1,50.
What I do now, we've only really got Aldi and Lidl in town and an expensive shop, I buy our meat in a cheaper shop a few km away, once a month and freeze it. Aldi and Lidl's meat are horrendously expensive. Out here in Germany, there is a difference of 50 cents for a packet of mince of 500g, pure beaf! If there is good pasta on sale for half the price, I buy that too, with two or three packs. Same for fruit juice. That is somthing we do not economise on. That is expensive, but it is the only luxury we allow ourselves. No soft drinks. Unhealthy and expensive too.
Buy things that are multifunctional. For example: buy a big chicken. You can eat it, then take the remaining meat off (if there is any), make curry or pasta with that (with cream and leak for example), or freeze for the same purpose, and then take the carcas and make stock of that, for risotto/soup/sauce (for sauce, freeze in ice cube container). Three meals in one. If there is any pasta sauce or ready mince left, you don't really NEED to eat it the next day, just freeze ir for a later time.
If anything is on sale at all, buy. In great quantities, unless you know that there are regularly sales on for the same product.
Be careful with sales though, because some of them are misleading. Like Lidl and Aldi, at least here in Germany, they marketing themselves as cheap, but they are in fact for some things more expensive. If the pasta on sale is more expensive than your regular brand, you can decide no.
Buy vegies which are in season, they are less expensive because they were not imported from places like India. We for example do not buy any tomatoes in Winter because they are too expensive. Too many vegies? They can be frozen, look on the internet for blanching times.
And for God's sake, ask yourself the question: 'Do I need this?' and 'Is there a cheaper option?' If you have had to chuck the last packet away because it had gone off, then do not buy a new one, you clearly do not eat it. Therefore, you shouldn't pay for it. If you have the problem that your cupboards are too full, make in inventory with dates on it so the tin of peaches doesn't get forgotten because it is in the back of the cupboard. And look for the cheaper option. Mostly homebrands are as good, only half as expensive.
Make your own bread/biscuits? With a bread machine that is easier of course. I am not sure how expensive the ready-made bread mixes are in the UK.
Make you own jam/chutney...? Easy and way cheaper, even if you have to buy your fruit. Chutney is dead-easy.
Put an apple tree in your garden 
. If you put any shrubs, make sure they give you something. Berries, nuts, or fruit. If they clog up your garden, they might as well do something for you. Terrace plants and herbs are also a good option.
Ok, so, good luck 
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PS: Mind you, there are only two of us, but there would be enough room for at least one more on this regime.