A quick telephone call and...
If you have passed one of the present Com or ATPL subjects before September 1, 2009, you can carry on with the flow you have started. So you write Human Performance and pass it before that date and you are okay. At now, from September 1 if you have not started the pass pattern, you will have to do the course.
This is not from a CAA source so treat the information with a lidded eye.