Just to add something, as I am in a similar situation at the moment.
If you do the ATPL exams and then the CPL flight test..... with the correct number of hours you will get your CPL.
I believe the problem occurs if you then don't continue on to do your ATPL within a year or so. As far as I am aware, you only have 3 years from passing the first ATPL ground exam to get your frozen ATPL?!?
Is this correct? If it is, and you don't intend to do the Multi/IR thing straight away, it may be a waste of time and money doing all of the ATPL ground exams.
Final question to the seasoned professionals, if you do the CPL grounds and gain a CPL, do you have to do all of the ATPL ground exams before embarking upon the rest of the flight training for the ATPL?
Thanks in advance
TBK