In the end I never had the scan.
Partly because my C6/7 disc at the base of my kneck was diagnosed on an MRI as being herniated probably causing my left chest pains.
All said and done I do in many ways regret not having it.
I did get a carotid artery calcium score, this is zero risk by ultrasound and gives a good indication of your amount of coronary calcification. Mine was low for my age, so it's very unlikely I have blocked coronary arteries.