Hi,
Am in a similar boat. I've around 8 stones to loose but would be happy with 6. I've tried every diet under the sun. Decided to try cambridge because I'm hoping for quick results to keep me motivated. Only day 2 for me today. I had to get my doctors signature because my bmi was over 40. He signed no problem tho. The signatures not to support the diet it's to confirm you don't have any underlying health problems that would contra indicate a VLCD.
Good luck if you decide to go ahead x