Failing a flight test always comes down to being under prepared. Don't attempt your flight test unless your instructor makes it very hard during a pre-flight test. He/she needs to make it harder than a real flight test. That way the flight test is easier.

Even if you are in your 50's it's never too late to live your dream. Most pilots who start second career did so because flying back then didn't pay well or for other financial reasons.

If you can learn the first 45 pages of the Flight Instructor guide Part ! Learning and Learning Factors you will do well.