My dad has cerebrovascular disease & smokes & drinks heavily, he's also awaiting an operation on his leg, i need to know the life expectancy please!

Nobody knows : Nobody can predict the future, and all physicians i know (myself included) have stories if those who lived years beyond expectations, and those that died early and unexpected from a litany of causes. Sounds like our dad is on a path to a premature demise, but when is anybody's guess, and the fact is nobody can accurately predict his life expectancy. Stay in touch with his primary care, and visit frequently.

Surgery: Your dad has selected all of the bad health combinations for cerebrovascular disease, smoking and drinking, especially heavily as these will increases the risk of any surgery significantly.

Life expectancy: No one cay tell exactly what life expectancy will be but it is very important that your father stop smoking, since smoking causes vascular disease to worsen nad may be cause worsening of his stroke risk and decrease the blood vessels in his legs. If he continues smoking and drinking heavily, his actions may significantly reduce his life expectancy.