If you could turn back time (and get that song out of your head), would you really do it? You can hold the teen angst, but we'll gladly experience that rosy glow of youth again. The problem is, when it comes to anti-ageing treatments there are more snake-oil merchants than you can poke an injectable at. Our articles, reviews and buying guides will help you get into the skin of your younger self, without losing your grown-up bank balance.