If you do not do your PGCE in the UK, then the chances are that many British schools in the UK will not accept its validity. Of course the better international schools that follow the English National Curriculum prefer teachers who are properly trained and experienced. They also require their teachers to have done their teacher training in the UK. Of course, there are plenty of Mickey Mouse schools in the Middle East and such establishments will be prepared to accept all manner of so-called "qualifications". I believe that there is some institution or other in Sunderland that will sell you an online PGCE, but any decent school will not even bother looking at this rubbish. Last but not least, there are the so-called International "Schools" where they Chew the Fat and they will employ "teachers" without PGCEs, degrees, brains, integrity or anything at all.