How to stop spending insanely on food?

Hi - I live alone in London and travel to office 4 days a week. I noticed my spending pattern and I spend shit ton on food and I am seeking ways to reduce it.

I buy lunch from local street markets on office days (£8-£10) for a lunch. Sometimes I buy a coffee in the morning, so £4 for that. This totals to about £200 a month roughly.

I buy my groceries from a big Tesco or a small Sainsbury's and spend like £200 a month (including stuff like detergent, soap, etc). I also buy ethnic groceries from Asian stores for about £50 a month. I am also a vegetarian so don't buy any meat (real or mock). I also am a teetotaler and don't spend on alcohol/smokes.

On some weekends I eat out with friends or sometimes go to my Sunday market and buy brownies/lunch etc. This amounts to average £100 a month.

Emergency Deliveroo £50 a month.

As you can see in total £600 for a single person and I think this is ridiculous.

How do you guys deal with food shopping? How do I reduce my food expenses? Perhaps I can start with stop buying coffee. Any advice will greatly help me achieve my goal. Thanks!!

Edit:

Thanks everyone, got some really good ideas and a much needed kick on my backside. I will avoid buying coffee and consider them as a once in a month treat. I will also plan meal prep and carry my own lunch to the office as much as I can. Apologies I am not able to reply individually to everyone, but thanks everyone for all your kind words!!