I’ve been widowed for 10 years, but have no problem shopping for myself. Granted, I have a decent income, so don’t need to count the pennies, and I spend £50-£60 per week on my main shop plus several top ups through the week. I do have a bottle of wine a week, but that is usually only £5.
I stopped shopping at Tesco as I don’t really like their meat, and now alternate between Sainsbury’s and Waitrose which are both closer to me. I like to spend a little more on better quality food, especially meat, which I buy in WR, and I don’t begrudge myself that. Also, I eat low-carb, so never buy bread, potatoes or rice (definitely not cakes and biscuits either!)
It all depends on your local supermarkets, and what their prices are.