Is it just you and your mum @Stonebag?
Because we have a household of 2 adults, 2 teen boys so it’s not going to help that much.
What do you cook? Do you prefer convenience? Do you have a fully stocked cooking pantry?
Have you got a pressure cooker, air fryer, bread maker?
On the cheaper end of the scale potatoes, onions, carrots, cabbage - ore expensive salad bags, avocados, decent tomatoes
If it wasn’t for my meat eating household I reckon I could virtually live on brown rice and dals, which could be easily cooked for pennies a day with ingredients that keep all week.
We get an online shop once a week mid week
How it works is we eat the food with a short shelf life first (bagged salad and fresh coriander), strawberries etc and work backwards so evening before next delivery it’s frozen fish.
We have a bread maker so make what we need that day
we get milk delivered twice a week (which saves us money because you don’t pop out for milk and come back with a French stick and houmous)
But we make most things, coleslaw, houmous, potato salad, bread, pizza dough, chips, ice cream, iced coffees, so if you have this set up and a cupboard with flours, tinned/dried beans, oils, spices etc the fresh food isn’t that much.
Labour is expensive, the more food you buy which involves labour, so flour and sugar v bread and biscuits the more expensive it will be.