Though I have not personally relied on Opentuition to pass F3/FFA, from looking at the course materials offered here it does indeed seem possible as they do cover enough. Good luck!
If you look through other comments you will see that many have passed using just our notes and lectures.
Do get hold of a Exam/Revision Kit from one of the approved publishers. They contain lots of practice questions and it is important to practice as many questions as possible.