I do this for the reasons you described, want to support local retailers - I have 2 DC and H and a cat .
My weekly budget for food is £115, and my area is quite good for it too - 2 big farmers markets, a local sustainable food co-operative (slightly pricey), a local greengrocers, big greengrocers with dry goods etc, cheap but great fishmonger, 10 mins walk or 5 mins bus away
Here is how it goes -
I spend £37 a week on an online meat order from a farm about 30 miles away (none closer who sell direct that i can find) where the cows and chickens are pastured and mostly grass fed with a little organic supplement feed, no anti bs - it gets delivered monthly and I get 2 whole chickens, 4 x 4 steaks, 2 x roasts, 4 x packs of mince, some sausages and bacon and 1 big pack stewing beef. I freeze the beef and lamb and cut the chicken into portions then freeze.
Then around £28 a week on the following -
-milk and butter (from waitrose my cheat items, because I love their proper full -cream milk and unpasturised butter and can't get it anywhere else)
-cat food and litter and cleaning stuff from pound shop (not the chain one)
-tea and coffee, weetabix, honey/maple syrup, flour, juice from bigger independent grocers
- eggs of the happy hoppy variety from someone I know with chickens
- 3 loaves of bread from independent bakers
That leaves me with £60
£5 per day on local cafe dinner when I work 2 days per week and childminder feeds DC afterschool.
£8 per day on the remaining 5 days to buy seasonal veggies and fruit from the nearest greengrocers (very cheap, great shop!) , and also stuff for recipes like stuff to make gravy, stock cubes, rice, nuts, beans, pasta, fish, cheese yoghurt, cream, treats (usually I bake with the flour and some of the eggs and milk and I just add sugar and a teeny little bit chocolate), olive oil, tinned goods, herbs and spices.
I look out for deals and reduced items as much as possible as my budget is tight, especially for the £8 part, and get some fruit (to freeze in bulk) and potatoes free from my family who farm sometimes. I cannot afford to buy organic fruit and veg at the moment. Anyway where I live there is only organic labelled veggies and fruit in supermarkets, and I don't like shopping there. There is a Whole Foods Market but it is EXTORTIONATE prices and possibly still counts as a supermarket despite them having loads of local produce, although some lovely stuff there.
I have been told I'm near the top of the allotment waiting list and it's 5 mins from my house so I will hopefully be growing our fruit and veggies by next year.
It is time consuming unless you have everything in one place, but I really do think it's much better. We don't tend to be able to have many modern foods like pizza or wraps, modern recipes etc though because the budget won't stretch to the extra ingredients and these things when bought cheap tend to have additives and preservatives, sweeteners (all of which I avoid like the plague). We have stew, casseroles, roasts, rice dishes like stir fry and kedgeree, mince and tatties, chilli, nut loaf, meatloaf, fish pie.
It can be done if you put your mind to it one step at a time. I don't miss the baffling "too much choice" of supermarkets, or the ready meals tempting my laziness, my DC don't see as many overpriced products AIMED at kids (even the organic disney character type kids ones annoy me, cause they just want want want anything packaged in bright colours or tv characters).
I started in earnest after watching the Supermarket Secrets programme and also having worked in a very large supermarket myself. The final nail in the coffin was when a very good local bakers, established since the 70s was forced to close because a new big tesco opened round the corner, I was really sad because I loved their pancakes and scones and you could see them being baked and the ingredients.