You have to love the work, first and foremost. If you think you want to learn the work so you can take over an established company, I think you may be setting yourself up for failure. I say that because it sounds as though:
a) you are not aware of the amount of time and effort it takes to become proficient in the trade
b) you believe that a few years at a company will expose you to all you need to know to run that business, and I can tell you with certitude that idea is not often true, and
c) you picture yourself as an owner first, and not an experienced technician.
Few others may be as direct as I have been, but I believe this is what you need to hear, and to think about, based on your stated objective. I have no other information about you on which to base advice, so it is based only on what you have posted.