Marks & Spencer is known for Jumpers (sweaters), Underwear, and a Grocery Store where they have containers of prepared food that just need to be baked at home.
We lived in Kensington and never have eaten so well!
My best friend from college moved to London (Hampstead) in 1972, so our trips there, after our previous one, we were more like natives, than tourists, because my friend took us to all kinds of places that tourists don't usually go to; though, truth to tell, we also went to quite a few touristy places as well, for the progeny.
Kensington is a beautiful area and I've been there many time. Love the museums and the Royal Albert Hall! Lucky you!