To help support your decision to get the surgery the main things apart from a basic GP/Doctor referral you need are
1- CT Scan of the chest / chest wall
2- Echocardiogram
3- Pulmonary function studies
4- detailed note from your family physician on any significant past medical problems including your cardiac, respiratory and genetic history.
The best way to get insurance cover is to make them see the surgery as a neccessary procedure and not just for cosmetic reasons as most doctors consider it these days.