If you are thinking of cosmetic surgery it may be tempting to head abroad for the sun and cheaper prices. But Heather Stephen warns  it may cost you more than you bargained for. Cheap flights and bargain holidays are not the only reasons we hop on a plane and head off to other countries. Now an increasing number of us are going abroad for cosmetic surgery. According to private healthcare search engine WhatClinic.com, travel for medical treatment has more than doubled in recent years. And the British Association of Aesthetic and Plastic Surgeons (BAAPS) says 20,000 people jet off from…