There is a lot of 'lean' ham, at less than 0.5% fat (as it is specified in the book) available here in the UK. Possibly the lowest, if the most expensive, is Weight Watchers own.
That is good news. Personally, I don't miss ham, or carbs, for that matter so you might say it is easy for me to just accept his recommendations. Now, if the good people at WW could please do something and invent wine, vodka and gin that are Dukan-friendly... that would be nice! *joking*
Seriously, though... Have pondered a lot on this over the years... Please feel free to criticise. To start with, there are several things at play here.
First, the plan is low calorie, plain and simple. I have been monitoring my menus (out of curiosity, mostly) with a toy I love, Dietpower software - no way, if you stick to plan, especially on PP days I could go over 1200; most days I force myself to stay in the 800-900 kcal range. If left to my own resources, I woould undereat - cos proteins are a natural appetite suppressant, they make you feel full, and as I don't eat out of boredom and binge only - but aloways - when I have a drink), I have had no problems. So from that point of view a miserable couple of calories coming from the muller yoghurts wouldn't matter. However what does matter, I think, the sugars, especially the fructose syrup, can play havoc with the blood sugar levels; even more so if one is susceptible to it. This, in its turn, might put you out of ketosis. And while it might not matter much for the featherweights (complimentary) who have little weight to lose, it might affect the marathon losers (like me, or anyone with 60-100-100+ pounds to lose); we heavy-weights have a more messed-up metabolism than someone who has more or les been "normal" all her life. Dukan likened deviations to the effect a pin has on a balloon, and sometimes a small deviation has as far-reaching consequences or even greater than a huge binge for another person. And we all know how demoralising a plateau is.
Second, and this again concerns more the marathon dieters - just cos I have experience with this - our stake to lose is literally bigger; we have to be more careful cos for us it is a long long way.
Please don't get me wrong, I am not against experimenting, quite to the contrary; but in situations like this I think that way: do I want it so much as to risk jeopardising my diet and putting paid to my efforts? No way fructose syrup, all the Es and starch in the world are worth it.
On the other hand some situations sometimes force us to choose the lesser evil; so yes, flavoured yoghurt is better than creme brullee; a grilled pork chop is better than potato salad and all that jazz. But that is another kettle of fish altogether.
P.S. Edited to add: diagnose your cravings; is it habit, boredom (including preference for heavily flavoured stuff) or are you hungry? Cravings are more likely to afflict you when you haven't eaten enough, and on this diet you have to eat to lose weight and avoid going into starvation mode. Often carb cravings are just our habitual instinctive reaction to hunger, and justifiably so - carbs raise the blood sugar levels fastest and are the quickest way to get the brain to acknowledge that your hunger pang is satisfied. The problem is on Dukan your body drives in lower gear and a carb snack, especially a fast-carb snack, disturbs the pattern. Luckily the solution is eat more of the allowed foods, small but often, and be especially careful around TOTM, in stress times etc. Another condition to watch for is dehydration, and it can also be misinterpreted as need for a quick sugar fix. Again, drink as often as you remember; if yu feel tempted by something, try having a glass of water, or tea with sweetener, and some bite of allowed something. Usually is enough.
Last but not least - thanks for the compliment, Jo, it is very flattering esp. coming from you!