My ob has changed my planned ceaser from 1 week early to 2 weeks early because hes going on holiday. should i get diff ob to give bub that extra week?

YES!!!: I think it is a sign of disregard for your baby's health to do this. He is entitled to a vacation but should have referred you to a different OB instead of wanting you to do this early. Every day your baby spends in utero is crucial for its health. I would change ob's not only to give your baby an extra week but to work with an OB who is more caring and responsible!