Hi, Megglevache.
I tried the Gentle Birth Method from about 28 weeks last time. It was fantastic, even though I didn't follow it rigidly. I did the course of 4 classes in London, plus listened to the CDs. The classes were for the self-hypnosis bit.
I didn't do the full diet, just cut wheat and sugar. What a difference that made! Low iron levels sorted themselves out, felt great and looked much leaner. And most importantly for me, my baby was a nice 7lb something...dd1 had been nearly 9lbs so was freaking about #2 being bigger and causing birth complications. Oh, and no weight to lose after the birth!
The self hypnosis was extremely effective in labour, right up to transition (and I am a real sceptic normally). The other areas it covers are optimal foetal positioning and perineal massage.
I think, particularly the self-hypnosis section, gives you confidence that you can have a natural birth. All in all, I had an energy-filled last 2 months of pregnancy and a fab natural birth.