Got so many tips off this thread, wanted to share some of my favourite M&S purchases -
lamb samosas (I tend to mix them up and eat lamb & veg 2 each as a meal with some cut up raw veg),
loaded potato skins (with some roast salmon fillets, rather more substantial side than my usual steamed veggies)
and I recently also discovered their handcrafted sourdough from the bakery, my favourite sourdough bread, and that's saying something since there is a lot of competition from artisan bakers where I live - if only it came in half the size since for a single person it is a lot of bread. I am experimenting with freezing it, to see if I can restore the freshly-bought taste