Thanks Whopity for the information.
I got the (b) on my rating however when reading CAP 804, the (b) :
(b) class and type ratings for single-pilot, single-engine aircraft, except for single-pilot high performance complex aeroplanes; class and group extensions for balloons and class extensions for sailplanes;
only exclude SP HPA complex. However the PC 12 is just an SP HPA, it does not have the complex in the EASA class and type rating list.
Guess I'll have to send a mail to Gatwick. Or ask them to revalidate my CRI based on my FI rating.