Welcome to the Support Board.
You can add conventional foods to your Cambridge Diet, but you want to be careful about fruit. It is basically sugar and will knock you out of ketosis. It is best to limit additions to lean protein and green vegetables. The exception with fruit are berries like strawberries. You can add a couple of them to you shakes without a problem. They are very low glycemic and will not cause the extreme insulin spike that other fruits like watermelon and bananas and citrus will.

It may not sound exciting but celery and Englis cucumbers make a refresing and crunchy snack. A lirttle salt or vinegar and it is very nice. I also like to have a mug of hot Beef or Chicken fat free broth. Nice and savory and warms me up on a cold day.

Is this your first time trying Cambridge?