There are 10 subjects to study but the some of the exams are combined into a single session. these are
Flight Perf & Planning
Air Law & ATC Procedures
Human Perf & limits
The single exam subjects are:
Aircraft Gen knowledge
Navigation
Met
IR Comms
I have one sitting left (hopefully!) in 4 weeks. The subject matter you study is the ATPL material, you are just asked less questions on it at the actual exam. There are also certain sections you can omit (not that places like Atlantic bother to tell you) that are also not in the exams. These are things like Mach meters, AC electrics etc.