I have been on a VLCD for the last 4 months (seeing doctor every 2 weeks).
I have found it really great, as I just need to see larger numbers on the scales to keep motivated.
I am due to come out of Ketosis next week for a couple of weeks, before going back in again for a couple of months to get to a healthy BMI.
My only advice would be to make sure that every day you eat lean protein and green veg in lieu of some of the sachets, firstly its phsically healthier for so many reasons, but secondly from a psychological point of view, I think it is good to commence a habit of eating lots of veg on a daily basis, and also getting in to the habit of eating meals which exclude empty carbs. In the long term I think this just might be one of the big solutions to keeping the weight off, ie not every meal has to include pasta, potatoes or rice.
(I'm not saying carbs are off limits for ever or anything, but I think for me, I need to re-structure my life so that most of my main meals aren't centred around them.
Good luck with the cambridge version!