You would only get exemptions from ground school if you have an ATP, plus some multicrew time (the numbers escape me at the moment). All it means is that you can self-certify, but given the nature of the questions, it would be a mistake.
Having said that, if you have a CPL(A) your course reduces to 400 hours, which means at least 40 hours in the classroom. FCL isn't clear whether that needs to be an EASA CPL(A), but we read it as an ICAO one.
Some schools don't require that much time in a classroom
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Phil