Seems quite expensive, might try this:
http://www.amazon.co.uk/Glass-Sealant-Inhibitor-Coating-50ml/dp/B00A3S1RGU/ref=pd_ecc_rvi_cart_1?ie=UTF8&refRID=08N5F3SJC6BF7CG07J0F
A little goes a loooong way with this stuff. And don't just do headlights, do any exposed plastic.
Black plastic under wing mirrors, plastic sill plates, engine bay plastics, B-pillar plastics, etc.