I found out that the Change4Life group created an app to tell you the sugar content in your food. I thought I'd mention it for anyone else who might find it useful. It's called Sugar Smart, you use it to scan the barcode on the packaging, and it will tell you how many grams. I've not given it a proper spin yet, but it seems to work on the few items I tried!
It says your GDA is only 30g, and I'm a bit confused because I always thought it was more?