The other thing is that during your PPL training you will probably have used higher speeds than the Vr and Vref that are in the POH. Simply because you could, and because instructors tend to want to have a few extra knots in their pockets, so that they can let you make mistakes without having to take over immediately.
If you are going to fly to the limits, particularly the limits of take-off and landing distances, it is well worth doing a few circuits (while lightly loaded and with a sufficiently long runway) where you strictly fly to the Vr, Vx, Vy and Vref numbers from the POH. You will find that the picture at rotation/initial climb and final approach is different from what you're used to.
Remember: Only if you fly to the POH numbers will you get the performance as described in the POH.