How much to budget for weekly groceries?

I’m an international student from Asia moving to London and need help in understanding how much to budget for weekly groceries. I have a health condition that requires me to eat a lot of fruit and vegetables for good hormone health. I’m a vegetarian. I will not be spending on bread, dairy or items made of flour. If relevant for understanding costs, my area of residence will be Surbiton. Any advice, tips or suggestions also appreciated. Thanks!

It will depend on a lot of things, such as which products, and how much, you buy, and where you shop.
Waitrose and M&S tend to be a bit pricier, Lidl and Aldi usually fairly cheap, and Sainsbury's and Tesco somewhere in the middle (although some products may be "price matched" to Aldi or whatever). Other supermarkets/places to shop are available. Also the "mini" food shops (e.g. Sainsbury's Local, Tesco Express) tend to be a little more expensive than the bigger full supermarket versions, as well as not having as wide a range of products.

Might be worth having a look at prices online?
e.g. https://www.sainsburys.co.uk/shop/gb/groceries – I don't know the area, but from Google Maps it looks like there's a big Sainsbury's in Surbiton.

Seasonal and local produce tend to be a bit cheaper than out-of-season imported-by-aeroplane things – e.g. carrots and apples are much cheaper than, say, avocados and mangoes.
Most supermarkets do "budget" lines, selling the "basics" for a little cheaper than the normal supermarket-label products or branded products.
And if you go at the right time of the day, you can sometimes get discounted food close to its best before date.
Would also recommend looking in the frozen section for some fruit and veg (e.g. spinach), and packets of dried lentils/chickpeas etc. instead of tinned stuff – takes a bit longer to cook but works out much cheaper (and takes up less cupboard space).

Also prices will probably change a bit between now and when you move to London – cost of living situation and all that.

Also – many supermarkets do some sort of loyalty card scheme – you can often get discounts or points when you scan your card when you shop there! e.g. Sainsbury's Nectar, Tesco Clubcard, Lidl Plus, myWaitrose card. These are usually available to download as apps, and for some you can get a physical card to scan, although I prefer to just use the digital version as it saves carrying round and remembering a bunch of cards.

Hope this helps a bit