My school never gave me my unmoderated assessment marks.
I think it's the board's policy that school's shouldn't give them to students because they don't really mean a lot in themselves (it also avoids having to explain the moderating process thousands of times when people ring up asking why their moderated assessment mark is 5 marks below their unmoderated assessment mark).
You can get your rankings from your school and you can also check them on the BOS website after they have all been submitted, to check they were inputted correctly.
You can also dispute them if you feel they're incorrect and have them checked.
All in all, there shouldn't be any mistakes in them (I'd hope every school would take due care in the whole process).