Hey Emma!
I'm very much the same as you. I have a lot to lose and am still coming to terms with how long its going to take me to do!
But I'm determined to get there.
I've done the Cambridge in the past and whilst it wasn't for me, I've heard of it being suitable for some. I am currently doing a 2 shake/2 meal plan and finding that a lot more manageable for me.
When I did the Cambridge I lost 11lbs in a week, but i only lasted the week before feeling overwhelmed. Ketosis was fine (not much poop though
) but I ended up feeling like I couldn't live like that forever. Everyone is different - only way to know is to try!
I wish you much luck! Hugs and stuff!