From the outset, I must admit that I have very little faith in "White Coat Syndrome" and even IF it does exist, there is a question of whether it should be treated.
However, that is a personal opinion.....now one needs to know if your raised blood pressure is a permanent feature of your life in which case it needs treatment my BP lowering tablets and the only way that can be established is by monitoring you BP three times a day for a week.
I agree with your GP.........