There is a phrase in England that one should not try to run before you can walk! That said, there is nothing wrong with starting your PPL with an ambition. You will need enough money to pay for the PPL, say about 60 hours and then before you can become an instructor you will need to gain 200 hours experience before you can begin. You will also need to pass the commercial theory exams, unless you only want to teach for the Light Aircraft Pilots Licence. During that time you may change you mind, or have other ideas. Instruction is not well paid and the PPL is a shrinking market with progressively less work for those who become instructors. You can earn more money teaching virtually anything else.
Some may say get a well paid job then you can afford to do the flying as a hobby.