It depends if you're doing the milk diet, or the low fat/low carb diet. You should get a copy of the diet sheet sent from the dietician. They prefer you do the milk diet, but since I don't like milk, I did the other...
Breakfast - 1 weetabix
Lunch - Small portion lean chicken or fish with salad or veg, no dressings
Dinner - Similar to lunch
You're allowed 1 slice of bread per day, unlimited black tea, coffee, nas juice and I think 2 pieces of fruit.
I'd double check though as I did mine 7 weeks ago and a lot's happened since... lol