Building insurance /Life Insurance on new build

I have recently applied for a morgage of 180k for 25 years getting a builder to do it .I need to get cost of building insurance (I think that what thery call it) and life insurance.Where would the best place to get the cost of building insurance and for how long ? Why such a vairy in the life Insurance ? I am 28 male non smoker. Fairly new to all this any help would be more than greatful.