OP, the first part of your description happened in the US some years back, the declaration of doctor shortages (particularly in "underserved areas".  That phrase always made me slap my head, because it's like saying there's no docs in this here area where there ain't no docs.), the building of more medical schools, but the outcome was very different than how you're describing present-day UK.  I'm not sure how that didn't happen, since in addition to medical schools that produce M.D.'s and D.O.s there are also plenty of APRNs and PAs (physician assistants if you didn't know) who can diagnose and prescribe treatment with few limitations.

But hey, we're all really fucking sick over here.

However, I met more pre-meds in college than I would have liked to, and I've seen so many egotistical or incompetent or nasty doctors that it's really goddamn hard for me to muster up much sympathy for their plight across the pond.  I've come to loathe the medical profession, in fact.  I still see it as a noble profession, don't get me wrong there, but those pre-med students aren't the first human beings to be lied to by the government and/or the media.  Hundreds of thousands of mutilated or mentally ill military veterans would back me up--even more if the dead ones could rise from their graves.

By the way, if you've got a medical degree but there aren't enough jobs in practice, there are a lot of other careers where that acquired knowledge and skill set would come in very handy and many companies in the health care industry that employ physicians in non-clinical roles.  Sure, that might not be ideal for the vast majority of unemployed doctors in the UK, but welcome to the real world.  People much worse off are getting a harder and agonizingly-sustained fucking over and have been for longer than we've all been alive.  Who carries picket signs around for them?