I have did Cambridge few years ago and have decided to give Slim and Save a go. Going to start on Tuesday when my products arrive. Have a couple of questions? Can you swap between lifestyle and simplicity plan. ie 4 shakes so many times a week and 3 and low carb meal rest week. Also if doing 3 packs and meal choice and don't fancy protein. Can you make up calories with semi skimmed milk as long as within calories and carbs allowance. Bit confused as did sole source on Cambridge so no food involved.