Cheers bose x...I have just reread FCL915FI and the pre-requisities for the FI course part (C) actually state hold at least a CPL(a) OR completed at least 200 hours of flight time,of which 150 PIC
When I first read it did not see the OR ! so the way I read it is YES you can do FI course with just a PPL providing you have the hours.