Integrated course students can, if they wish, do all the flying (inc IR) and then go back to do the exams. This is what a number of people have done over the past 12 months in order to allow the chaos of the new JAA ATPL exams to settle down.
However, if you are a modular student you must have passed all 14 exams before you sit the CPL Skills Test. Some schools won't even allow you to begin training until you have the exams passed.
That is how my FTO explained it to me. I will, of course, stand corrected if anyone thinks any different.
Good luck with the resits as well
Regards
RM