I have private healthcare through my work. I called them to ask how I would be treated for Diabetes via the private route instead of going through the NHS.
I was told I could see a specialist (that is registered with my private healthcare provider) for tests etc. and once confirmed then I would be entitled to two dietician visits and two some other thing that I can't recall.
Basically, a chronic condition that require continous treatment is exempt on my healthcare plan.
So you're best to call and find out what you're covered for and what is exempt. The NHS have been great to me so far, apart from gently discouraging me from self monitoring and denying me testing strips.