GCSE'S Will form part of your "Key Skills" and would be required for any framework Apprenticeship.
At 24 I think a number of possible employers would think twice about you on the Apprenticeship route due to the increased cost (Funding Reduces as you get older, 19+),
Have a look at the City & Guild Web site for Aero Level 3 requirements
Also
BTec & EdExcel
ATB