You can start by reading books like Red Herrings and White Elephants: The Origins of the Phrases We Use Every Day by Albert Jack and Ama Page. It seems to be out of print but you can find it for free on Scribd and possibly at your local library. They really only work infrequently. It’s fine to throw in a “good intentions doth butter no parsnips” in response to an amusingly inconvenient situation once in a very long while but if you go round using them all as much as possible you’ll look a right plonker.
I’ve been thinking and surely after all this, they can’t possibly disband the NHS right? It’s all “NHS NHS NHS!” at the moment, it’s blatantly obvious we barely have this under control with the NHS we’d be fucked without it, would it not be political suicide to touch the NHS for at least the next few years, it’d be like finishing WW2 then talking about disbanding the military in my eyes, utterly insane in normal circumstances let alone current/recent ones.