For your PPL you only need a class 2 medical. However for a commercial pilot you will need a class 1. In your PPL you will learn general handling, emergency procedures and navigation, if you go to your local flying school they will tell you exactly what is involved in getting the PPL. The commercial route is a long and hard process however if you are willing to put in the work then obviously your dream job will pay off. I suggest you do some of your own research into it. Talk to some flying schools look at a few posts on here and you will find lots of information on the different routes to become a commercial pilot. It does cost a lot of money and there are questions raised about how easy it is to get a job, but people are doing it and people are getting jobs so it is possible. Hope this helps.
Ed