I use Manuka Doctor oil. It's certainly not for chronic severe acne, but more for occasional spots which it reduces the size of. I've also noticed scars from spots vanish quicker since I started to use it. I use it once a day after washing my face with the Simple Facewash.
Also can't emphasize enough what others said about diet. Ditch all the ready meals and takeaways cr*p as much as possible. Cook fresh veg and (preferably) white meat from scratch and eat plenty of fruits as well as drink water.