I've used value cleaning products with no problems, if you clean every day why would you need strong detergants? I use sp toilet cleaner but I've switched to astonish for the cleaners from the pound shop because I like the orange oil cleaner.
I've looked at your list and had the following thoughts.
Pastry can be made with trex and smartprice plain flour, I make mine in a food processer using chilled water and I quickly pulse the fat and flour before spooning the water in. It takes seconds. You could make batches weighing 500g or whatever the quanity is that you usually buy it in and freeze it. It freezes really well, I even freeze offcuts and save it all for mince pies.
Squash isnt really needed, it's nice but it's not essential.
Same for fizzy drinks too, bone stripping and chemical laden.
A breadmaker would save you money, you could make dough for bread rolls or pizza bases. Much cheaper than shop bought pizza and nicer.
Wraps can be made, there was a recipe on here ages ago from the allrecipes site and it was very easy and cheap. Again things like this freeze well.
Herbs can be grown so easily, I used to grow them in a small strawberry planter on the windowsill.
If the cat wont change food (and I know about cats and their food refusal they make toddlers look easy) could you source it cheaper off the internet?
The organic yoghurt, do sainsburys not do an own brand version? you can get yoghurt making kits too. Lakeland do them but are really pricey ime so again the internet is your friend.
I would imagine the asian supermarkets do rice cheaper in big sacks than aldi or sainsburys do.
Apple crumble is a cheaper pudding than cheese cake and is easy to make and freeze ahead.
I dont buy joints of beef unless it is marked down, I buy big sirloin joints for £5 from morrisons. Mince based dishes are cheaper eg cottage pie, chile.
I would ring around a few local butchers and see if they are cheaper on orgainc meat/chicken than the supermarkets are per kilo.
I would try sainsburys basic cake mix for making cakes, it's very cheap and you can bake a cake while something else is in the oven too. You could do it as fairy cakes or as a round cake.
For fruit I would buy bananas, apples and oranges with whatever fruit aldi have on super six for variation or tinned fruit in juice from sains basic range. I wouldnt get strawberries when I'm trying to get the bill down.
Have you tried the local markets for fruit and veg? farm shops can be very cheap for potatoes but the crops not great this year so prices can be expected to rise eg last year 2.5kg of wilja were 70p, now their 90p at my farm shop.
But you know how much time you've got to shop around and batch bake/cook.