At about 19:30 in the film Dark River (2018) - Tubi, a sheep has broken its leg. the farmer pays a vet £20 to kill it and then hires a knacker to dispose of the body.
The farmer later shoots, skins, and guts a wild rabbit, so it's not an issue of being squeamish.
Is there some law in the UK that prevents the obvious action: the farmer's slaughtering the animal and having it for dinner?