My understanding is you have to get a consultant to agree it is an outstanding case. His NHS Trust then applies to the Home Office. However, those sensible civil servants have decided that the NHS Trust (part of government) has to pay a hefty fee to the Home Office (another part of government) to make the application. The NHS being strapped for cash, it will refuse to pay.
It seems once again the politicians have said one thing but the reality is another
Of course you can buy it legally in many other countries who accept it has a number of medical uses and is not going to rot your brain. but you cant import it..........