I don't live in the UK, so of course I can't comment on particular shops etc.
But, do you have factory shops? Shops linked to a certain manufacturer where you can buy in bulk or possibly even because there is a small fault with the product.
I never buy cleaning material in a normal supermarket. As these I always get in bulk and they last me 6 months or even more sometimes. Like for an example I have in 15l of fabric softener in right now, which is the wrong colour, so it was on clearance in 5l containers. It is a bit of an outlay at the time, but it cost so much less than supermarket prices. I actually get quite a shock when I see the prices of washing powder, and just general cleaning items in the supermarkets. The same with toiletries. Shampoo/ soaps etc are all bought in bulk. Also when there is a really good offer, then I will for eg, get 3 deodorants, which then can be off the normal shopping list for a while. In the meantime I look around for other bulk deals and keep a bit of a stockpile going. So when I do go to the shops (I only shop every 2nd week), then all I need is food, and not all the other things that really cause the total to add up.
Also, do you have the cheap shops that sell off the items that are close to their sell by date, or actually just passed the date? I don't get too upset if I can get shampoo or body wash that is due to expire within the next month, as how off can it really go?
And I am really not too brand fussy now. I have tried most brands and if I decide one is a no go, then I won't buy it again, but tbh a lot of the time, the in store branded items are not terrible. Talking things like tinned food, cereal etc.
I used to just have a habit of buying the same thing. But I don't shop online, I go into the shop and then am able to pick and choose better, rather than just repeating the last order. Not sure about for you there, but a lot of the time in the in store specials are much better than online ones. It is a good way to experiment with new things, different brands, but you have to use them... no point getting something new to try and then not incorporating them into a meal.