Hello Nick,
The minimum age for CPL is 18 years so you don't have to worry about that. Age limit for full ATPL is 21 years, however it will take years before you'll get full ATPL anyway because it has plenty of limitations. Remember, that after you graduate from flight school you'll at first have CPL and fATPL. The small "f" letter means that your ATPL is "frozen" until you have at least 1500 hours so in a real life this means a couple of year working as a F/O in some airline. So the age isn't an issue with ATPL either... Basically you don't need ATPL before you will be a captain, but most airlines require "frozen" ATPL to work as a F/O.
I hope this helps at least a little bit... Have a great flights and happy landings!
Best Regards,
Approaching Minimums