Hi there peaches i have used bio oil and i think its great stuff, surgeons here recomend it after breast surgery as it makes the scars go away i have no stretch marks on my tummy i used it while pregnant.
It can be bought from your local chemist
.: Bio Oil :. the site will tell you if its available where you are if not your second option is ebay.
Its not cheep but its worth the money for sure they scars and stretch marks gradually fade to nothing with continual use.