hi, i am also from the uk.I am under prof mathias and he is lovely so don't be scared. When i saw him he wanted me in hospital for five days of tests. I had a tilt table test,mri,eeg and some other ones that i can't remember. Have you been diagnosed with POTS? In my forst appiontment with him he took my medical history of symptoms and did all the normal neurological tests. I hope it goes alright. best of luck and don't worry. take care. H x