i think I've just replied to a few threads with this now so you'll probably see them all at one! You can do 3 packs but you should have the extra protein if you do (100 g of chicken or white fish) as otherwise you could suffer from muscle wastage - which would mean you would have a much lower metabolic rate at the end of the diet and it would be hard to keep the weight off. Not what you want!
You can drink water (still or sparkling), water flavourings from SnS, black coffe, black leaf tea, peppermint tea, green tea. No tea with flowers so no camomile tea or green tea with jasmine. You can't have lemon in your water either. A number of people also drink Marigold bullion although it's not on the official list. I think there's a good thread on drinks in the Exante forum.