I used to have a link to the medical requirements for the NPPL but can not find it so quickly.
Anyway dont be fooled in thinking that all GPs are happy just to sign on the dotted line for a couple of tenners.
In todays busy and 'red tape' world quite a few have got cheesed off with signing forms for just about everything.
The form requires the same effort as one for an HGV medical.
Some GPs will therefore charge the same. That currently is max. £92-50.
FD
Edited as I found the link:
http://www.caa.co.uk/docs/49/SRG_MED..._%20Jan_03.pdf
and further information re conversions etc can be found on:
http://www.nppl.uk.com/