In the "good old days" I needed to pass a ground exam on PPL subjects and 150 hours P1 with my PPL to start an FI course. On qualifying I then earned peanuts for the next 25 years as a QFI, getting my CPL and ATPL in the fullness of time. I wanted to instruct because I had learned very cheaply and wanted to put something back into the movement. I have never regretted it. These days, if you don't want the enormous expense of getting a CPL, then adding to this the cost of an FI rating to, like me, earn peanuts I would seriously look at becoming a microlight instructor. They didn't exist when I started.
P.P.