Every supermarket has a value or basics range. How do you know what is worth buying and what to avoid. Below is purely my opinion but I hope you find it useful.
Baked beans and spaghetti are fine in fact I've found value ranges don't have the excessive amount of sauce filling the top half of the tin that the more expensive brands seem to have.
I've not yet found a satisfactory value pasta sauce - if anyone knows of a good one PLEASE let me know however value pasta is perfectly fine. As is rice and other dried foods
No frills frozen veg is fine although, I've found with the peas especially you need to cook them a little longer.
Value raisins and sultana's are perfectly fine. If your children like to take raisins in packed lunches or as snacks in those little boxes use the value raisins to refill the boxes. That is if you can stop your children destroying the box after they've eaten the contents.
Cereals and biscuits are also fine. In fact the biscuit barrels are very good for large families.
Value vegetables are also fine although sometimes need a wash. Be careful with vegetable pricing sometimes something branded as value is not always cheapest and don't completely disregard pre-prepared vegetables they can often prove to be the least expensive. Don't ask me how this happens I don't know but pay attention to the price per unit which will be displayed under the price.
Never, never, never buy cheap meat or fish. This is one area where I believe you cannot economise. If you do eat meat make sure the animal has had a good life & that you use as much of the animal as possible. If you buy a whole chicken use all the meat and make stock from the bones. If you don't have time to make stock immediately you can freeze the bones to use later.
Another thing to be wary of it tea, coffee and chocolate I always buy fair trade where possible again it's a matter of principle. Good news however is that Sainsbury’s basics ground coffee is fair trade and only £1.69!