annaje
a) if the cottage cheese is only around 1.5% fat its fine, think about it, there is fat in meat and thats allowed..... I personally wouldn't worry about having a little more fat in the cottage cheese, because I rarely eat meat so my dukan diet was very low in fat. If you eat a lot of meat then maybe a good idea to watch the fat elsewhere, ie in the cottage cheese.
b) I used quorn mince and quorn chunks which are low in carbs - basically just mycroprotein and eggs, not sure whats in the sausage, avoid if it contains added starch/carbs. I also had the marinated tofu as a snack...
c) yoghurts - all mullerlight contains added sugar (fructose) as well as sweetner. Enjoy as a treat, but its cheating. TBH I haven't found any flavored yoghurt that has no added sugar at all. Also yoghurt contains a lot of milk sugar - (the best yoghurts are total 0% greek), only 4g of carbs per 100g. Cottage cheese is lower in carbs than yoghurt (similar to the greek yoghurt).
So yes does allow other yoghurts, but for me I got better weight loss with less dairy (all my dairy was natural yoghurt & cottage cheese) and more vegetables, and so gave up on the PP days! You'll have to see what works for you.
So yes, have the mullerlight as treat, but living on yoghurts is not going to result in the best weight loss.