The Defra regulation states:
"
The fed ban extends to the feeding of catering waste to farmed animals. Catering waste is defined as 'all waste food, including used cooking oil, originating in restaurants, catering facilities and kitchens, including central kitchens and household kitchens'.
"It is illegal to feed farmed animals catering waste that contains or has been in contact with
animal by-productsas this is a potential source of disease. 'Farmed animals' includes any pet animals that belong to a farmed species, such as pet pigs, goats and poultry.
Catering waste includes food waste kitchens, including domestic kitchens, retailers, food factories, distribution warehouses etc. that contains or has been in contact with animal by-products (such as raw eggs, meat, fish products). The ban includes the use of Used Cooking Oils (UCOs) originating in restaurants, catering facilities and kitchens, including central kitchens and household kitchens."
I guess the query arises whether you can guarantee/satisfy yourself that supermarket surplus fulfils this. It might - but Im not sure how an individual could be sure of what happens in the process lines. The animal feed people can, as they are doing it on a wholesale basis so can inspect the specific production lines etc, or else get the waste from a point in the process they know to be 'clean' which isnt used for any non veggie products etc. I think they do also have to get approval too so there may be an official check on the production facility too. ie the OK would be for specific products from specific supermarket production lines.
In practice to give bread bought in the normal way and which states all veggie ingredients and which doesnt have any warning stating (as some veggie products do) 'may have been made in a production process where animal products are used' MIGHT be enough to convince the inspectors that you are following the rules. It depends whether they had a bad day or want to make an example out of someone, as I dont think it has been test-cased.
Certainly anything 'skip surfed' could not comply as it would be highly possible it could be contaminated with prohibited products whether apparent or not.