I think I am having the same problem. I find a flight time and price that works, then try to see if I can book the same time at the BA. I didn't hear back and then that flight is no longer available.
Book the flight first...maybe hotel too. Then worry about the diving. I would not wait a week to buy airfare because I could not reach my dive op. Of course I know how to use a telephone and get an answer in minutes.