i am mainly concerned with the lung function testing.
The honest answer is, if you're tender in age, and you havn't got any pre-existing disease, then passing a medical shouldn't be an issue. Fags or no fags.
You run a slight risk of dying of an'orribloe cancer in about twenty or thirty years, more of a risk of dying younger or being disabled by a stroke in mid life, or at best, living as long as Uncle Albert.