I too am in the same boat regarding the NPPL. I couldn't get a class 2 medical because my uncorrected vision was a teeny weeny bit over the arbirtary point the JAA med people thought was appropriate.
My GP also had never heard of the NPPL but he did know about the DVLA requirements. I took along the information from the NPPL website entitled "information for GP's" and he was quite happy to sign the form on that basis. The NPPL medical is exactly the same as the DVLA HGV drivers declaration without the uncorrected vision limits. Tell your GP that and he will understand what he has to do, oh and by the way my GP signed the form for nothing! what a refreshing change to everything else in aviation
Now all I need is some decent weather and maybe I can go solo, 55hours and I am more than ready
