They sell frozen bumbarb in Asda and I saw it in Waitrose the other day too.
Bumbarb
KidA - not all "sugars" are equal.
The sugar in fruit is fructose, which creates a faster, higher insulin surge in the body, and gets converted into glycogen and fat very very quickly. This is why there is so much concern about "High Fructose Corn Syrup" in sodas, ready meals etc.
Other sugars - like the lactose in milk products, aren't digested quite as quickly, and don't cause same the insulin peak.
As Anja says, rhubarb is allowed on the diet, and we are in the middle of the rhubarb season in the UK - so why not buy some, bake it with a little splenda, and then stir it into your zero-fat yogurt?
Muller toffee and vanilla used to be ok DuKan until a couple of weeks ago (per the official website).
2 x fat free yoghurts with fruit pieces used to be the official ok on Cruise - both counting as "tolerated items" - you've probably read about those. Ill advised if near your target as they tend to slow things up, even stall us.
Those M&S ones you mention are certainly better on the carb levels BUT they contain 0.1% fat. Over here, fat free is the recommendation. Anyone tried those M&S ones and got away with it?
With all the dairy confusion in the UK, I think it's a case of trial and error to be honest. As you're not that overweight, I'd exercise caution as heavier people would probably get away with more than you might.
Basically, fat free Total natural, or fat free quark or fat free fromage frais/blanc are the best. Sweeten them yourself. That's the best advice I'd dare give now.
HansPan - the only thing you mention which really is a no no is the extra lite soft cheese (philly?). It's a tolerated item in Cruise only, 30g a day. Fat free isn't easy in the UK.
That cream cheese usually has a two month sell by date... so I'd hang onto it for longer still