Hi GT....I think the milk week is important personally. At least a partial attempt is better then none. It is a lot to ask of our bodies - to sustain on just 500 calories and a few liquid meals, week on week. I felt it was a good sound idea to give it something it could actually digest.
I did the milk week, but not the full amount, and mainly used it for adding to hot drinks.
You can still do it - even if its the following week. I did not gain. Yes, the loss was probably smaller then other weeks, but soon made up for it the week after.
Just be careful in why you make the decision to skip it. It could do your body good. We don;t see much of you here, so I don;t know if you have had any light headedness or dizzy spells at all during the diet. If you have, I would suggest you do have some, for health purposes.