If you are looking for website that has cheap recipes on it try www.hillbillyhousewife.com
It is full of really cheap recipes for using dried beans, mince, rice etc. Also have a look at wartime cookery books for ways of cutting back and making things go further. Recently I made a leg of lamb feed the 5 kids for 5 meals and made soup with the bone stock by using wartime methods, same with a chicken. Another good website is the british potato council one which is full of good recipes for using potatoes.
I think that you could easily cut back a bit if you plan tightly enough, make the most of things and stretch food. I have a family of 7, eldest son 20, youngest over 7, and I spend perhaps 80 or 90pounds a week on average. I have to say that ecover is my luxury, as well.
We eat quite a lot of dried beans, barley, rice or lentils and only use a small amount of meat. This weeks meal planner is
lunch:
bean and ham soup x 2
pasta salad
lentils and rice
eggy rice
sausage burgers using hm sausagemeat
mash with roots and greens and baked beans
dinner:
lentil loaf, wedges, mixed veg
macaroni cheese, broccoli and cauliflower
garden veg rice and beans
mincey rice
shepherds pie topped with the same mixed up mash as above
curried cabbage and potatoes
creamy tuna with rice and peas.
For breakfasts we have Asda's own shreddies, hm scones, oatmeal muffins or pancakes with butter and syrup. Desserts are banana loaf, melon loaf, madeleines and oat and raisin cookies. Snacks are fruit, yoghurt, ice lollies or more of the muffins and stuff that I baked. I make all my own bread and stuff as well because it's cheaper.
As somebody already said, plan meals around the carbs and then add protein and veg. It works out well, that way. Or, what you could do is bulk cook beans or lentil and rice and then make them into several meals.
A 1lb bag of green lentils with 1lb of brown rice can be made into lentil loaf, lentil burgers, tacos/tortillas (by adding tex-mex spices.) A couple of pounds of dried chick peas can be turned into chick pea curry, falafels, hummus, spicy chick peas with cous-cous...This is what I had to do a couple of years ago when we were kitting out DS1 for uni. Then I only had about 50pounds a week to buy everything that we needed for all seven of us.
I serve some kind of bread or tortilla thing with almost every meal to bulk things out and have soup for a couple of meals a week as well. I also try to buy seasonally and grow stuff in tubs in the garden to save more money. It's a bit late now for this year, but you can grow potatoes, carrots, courgetes, tomatoes, cucumbers etc. really easily. I converted the children's sandpits into planters for courgettes, celery and things and just use big pots for everything else.
Another good website is Approved Foods. You can buy things really cheaply there. They are a bit past their best before date, but still fine and ludicrously cheap. I bought a 2kg jar of LLoyd Grossman pasta sauce for 99p which will do for about 4 meals ans angel delight stuff for 10p a packet.