Hi Helen, you poor soul, I wish you all the best.
I'm generally a big fan of following proper medical advice, but it's true that the nurses on a general surgical ward in the UK often don't know what they're doing with bariatric surgery, or anything unusual. Nursing staff, even sisters, can be very rigid in going by the book. I mutinied a few times after the initial sicking up of that pill and made sure I checked with either the consultant or the dietician before I did what they told me. In particular they didn't seem to understand that "nothing but clear fluids" means "no huge pills".
As for the milk and yoghourt diet, my consultant told me not to bother as she was happy to do the surgery without me going through that. Maybe at 22-odd stone I wasn't as obese as some who do it, but I thought it was an interesting difference - I missed all the pain that a lot of people seem to go through trying to maintain a really horrible diet. And I don't seem to have had any worse after effects than others, to judge from the boards. But maybe I was just lucky with my consultant; I wouldn't advise trying it if yours says differently.
I have to say, having tried and failed miserably to stick to milk products only after the op, I certainly wouldn't have managed it with my whole stomach and ordinary appetite beforehand!