See paragraph 2.3 of the NPPL document:
http://nationalprivatepilotslicence....20REV%2011.pdf
A NPPL adviser will assess your experience and provide you with an individual assessment. You must complete the training and examinations stipulated in order to obtain a UK NPPL. You can then apply to the UK CAA as a paperwork process only to convert the NPPL to a EASA LAPL(A) in accordance with CAP 804, Section 4, Part P, page 11.
ifitaint...