If you familiarise yourself both with the flora of Greece and Cyprus, and the commonest source plants for the compounds that interest you, you should be able to see where these two lists overlap. Both of these sets of information should be readily available. I would suggest you purchase field guides for Greek and Cypriot plants and take it from there. This type of learning journey will be very valuable for you.
As far as the law goes in those localities, that is another thing you can look up for yourself. Governments nowadays typically have all their laws available for perusal online.
Stay safe (and turn off the caps lock a bit
)
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli