Is there a calorie-counting iPhone app that knows about UK foods?
I use the MyFitnessPal app when on my iPhone and I use their website when on my Macbook Pro and find them to be easy to use. They do list the foods you're mentioning on their website here (the list is enormous, look around):

http://www.myfitnesspal.com/brand/list/585

I'm in the USA so make sure they have the foods you want before signing up / buying the iPhone app.