I do buy at M&S: pants and socks for men, women, kids. Tights, pjs, plain t shirts. School uniform. Lunch.
I'd love to buy but can't find it there: simple jumpers and cardis, in wool, cotton or cashmere (NOT cashmilon, that is acrylic, I CAN tell), many more tshirts than I do, no glitter, ruffle, patterns... white cotton shirts, straight legged trousers, breton tops and navy chinos.
Would never buy: plastic clothes (acrylic or whatever), patterns beyond stripes, evening wear, anything sparkly.