Probably too late for you but it might help someone else. It’s very easy to get a taxi from Kuantan airport. Just go to the taxi counter, get a ticket and off you go! It was 220 MYR. On the way back, we asked Reception to book us a local taxi and that was 250 MYR. So a lot cheaper than the hotel transfers.
Many thanks Sophie. In the end we decided to hire a car, very cheap, and easy driving.