Barley, 500g bag, 55p [1].
Some sort of Polish flour [2].
Butchers aren't allowed to sell beef bones, due to the 1990s BSE crisis, but the others are no problem. They may well not stock them, especially in a supermarket, where they are somewhere between a glorified cashier and an actual butcher. You would need to build a relationship with a local butcher to make your unusual requests worthwhile -- it might mean he orders them, or that while preparing the meat he doesn't throw them in the bin (at which point, they can't be sold).
> "Nah mate, health and safety mate, can't sell you these"
This is modern British English for "I don't want to" or "it's not worth my time" or "go away, you are complicated". It's rarely an actual rule.
[1] https://www.tesco.com/groceries/en-GB/products/256538041
[2] https://www.tesco.com/groceries/en-GB/products/275505155