The only way you will get to where you're looking to be is to be good enough to attract the attention of the clubs. There are so many 16 year olds playing at a "low level" that you won't be attractive enough to anyone for them to pay you.
A lot of clubs have what is called an academy where you have the skill and expertise of the club and they will help train you, however it is unlikely you will get any form of payment until you sign for the squad. Not much money in rugby! Good luck!