You will have no problem mate, I am similar to yourself, in terms of a BMI.
One thing that you will find when you join an airline is the cabin crew will force all this crew food down your neck and constantly feed you crisps, chocolate, force beer down your neck on night stops and very quickly you find your waist line expanding and those once snug fit uniform trousers become even snugger
.
It is time for me to knock the crew food on the head and get my fat ass down the gym
.
Enjoy your flying.