Ok so here are some basics I use
Oats – I use lots, usually get supermarket cheap brand
Berries – use frozen its cheaper
Greek yoghurt – lidl do a huge bucket 1kg, its lower in fat and high in protein
Chicken lots of it – I buy frozen fillets as more cost effective
Peanut butter if you like
Rice cakes for above
Cottage cheese is good if you like
Lean Red meat is fine but chicken is best!
Lemon & lime
Water, if you hate tap get 7 1.5l cheapo still water bottles and chill them – take 1 out a day and don’t go to bed until empty! Try and build on the 1.5l and drink more each day
Eggs – I get 30 a time from home farm shop, £5 so cheapest around and they’re so big and lovely. Plus free range
Broccoli – again I use frozen
Cucumber – I chop them into sticks at the beginning of week and store into clip boxes. Easy to grab on the go, and also handy for the baby and kids
I use my local farm shop when possible. Always for eggs and I get frozen chicken breasts from there too when on offer. Lidl is great for the yogurt, nowhere else stocks it as cheaply for the volume. I get nuts, oats and seeds from there too. Pop to your local health food shop, stock up on herons and spices. My local one sells them by the 50/100g bags and they work out very cheap!
Obviously on top of this I have other fruits & veg, and other things. These are just staple foods. I will add to it.