£40 for three or four days. Your cats must be expensive ! Or veggie food is more costly than I thought. I spend £60 a week for teen ds (hollow legs) and myself. We aren't veggie so eat meat/fish 5 nights a week.
This week we had
Chicken (legs), spicy couscous, peas & sweetcorn
Chilli & brown rice (beef mince)
Omelettes and oven chips (cheese & assorted veg)
Pork chops with apples & garlic, and salad
Haddock, peas, brown bread & butter
Friday - Pepperoni pizza for ds, risotto with mussels & hake for me
Tuna with garlic & cannellini beans
Lunches are pate, salad, home made soup, sausages rolls, beans on toast, cornish pasties. Breakfasts are toast and fruit. Snacks for DS are fruit and supermarket biscuits, nuts for me. Main shop is Tesco. I'm a full time working single mum so nothing I cook takes more than 5 mins effort. (except risotto). I live rurally too.
Your issue is shopping in the Co-op. Can't you do an on-line shop somewhere sensible? It would be better value. Or ask a neighbour to take you to the supermarket once a week while you are poorly.