(UK) Moving back into a London flat and need to save on food shopping where I can. Any great food shopping hacks, recipe ideas or clever tips?

My work is forcing a return to office so to cut my commute and save my mental health from spending hours on a train every day I am moving into a small London flat. Any tips to help save on food shopping?

I have no problem doing batch cooking, buying frozen, in bulk or whatever ways I save cash - open to all suggestions.

Thanks everyone!