My husband is a professional photographer and it amazes me how much goes into getting excellent quality photos. He mainly does weddings and the detail is awesome. From how people are holding their sholders to how far apart their fingers are on the bouquet. Lighting is always an issue... Fore ground lighting, background lighting.... Knowing how to pose a tall thin groom with an overweight short bride.... The list goes on.
I personally would do the course. To get the really good pics you need to know more than just standing people next to each other and snapping away. Especially if you are wanting to get paid for it.

As for your question about getting started, my dh's parents are both professional photographers so he started by working with them from his teenage years. Now he has an assistant that he is teaching. So if you could work with an already qualified photographer that is possibly another great way to get into it.