Hi jetplanepilot,
So you need to approach Fujairah aviation academy, and they have specific courses which you need to complete in order to convert your ICAO CPL to a GCAA one, you can get in touch with them and they'll help you with the costing, which is around AED 30,000 i believe and you have to fly specific hours with them on C172 and DA42 if you have ME. Along will all that you will have to go through ground school and sit for the 14 GCAA exams. In my opinion, don't do the conversion unless you have a job in hand, because all the national airlines do it for their hired pilots in house.
Cheers!