with regards to how ATPL module could be a degree. i think that degrees are tailored to a certain profession and so is making the student adapt to the industry or job. so that's my view as to how it could be offered at the degree level.
the level of academia required for ATPL groundschool is definetly higher than GCSE however. i don't really know why the minimum requirements are only at GCSEs level but nevermind, i don't make the rules. i certainly don't recall integration and differentiation at GCSE. you don't have to carry out these calculations but without the knowledge, i dont see how someone could fully understand what is going on. oh, i am referring to the study of INS for the above.
overall, it is quantity rather than difficulty thats the main challenge but i definetly think the level is about A level standard. come to think of it, you have to be 18 to get a CPL/IR anyway, so a school leaver would have to wait a couple of years.