Don't forget though that to start the FI(R) course you need a PPL and 200 hours in addition to the JAA CPL or ATPL theoreticaly exams passed. You will not be able to get paid as a PPL/FI(R) (at any level of instructing).
So, as long as you pass the class one medical, you might as well do the JAA CPL skills test as well. This will enable you to be paid to instruct.
To obtain further instructor ratings, you will need to take the restriction off your FI rating. This involves signing a certain number of students out on solo flights, minimum number of instructional hours, etc.
Then you will need to attend a course for each rating you'd like to add to your FI rating. This includes Multi Engine Instructor, Aerobatic Instruction, Applid Instrument instructor.