Exam groups
If i remember correctly:
The subjects are spread over 5 days, you can take whatever exams you wish.
You may only visit the examination centre 6 times, and you have a maximum of 3 attempts at each exam. Different schools advise different techniques. My advice would be to contact your ATPL training provider. If you don't have one, contact Stuart Smith on Uk 01234 757969. He knows his stuff, runs ATPL Groundschool