A Barrister by the name of Peter Telford QC has written a useful free guide for people who need to make applications to their PCT for specialist funding - e.g, for drugs or treatments not usually available within the NHS (usually those that have not yet been approved by NICE).
Mr Telford successfully fought for funding for his sister, but sadly, this came too late.
I think this is a useful starting guide, and my understanding is that patient who want to access the interim drugs fund will need to have exhausted this pathway first - but check this.
southernhaychambers.co.uk/docs/your_patients_right_to_treatment.pdf