I always buy the (Harley's) sachets (for storage convenience) and make them up myself into a tupperware... I never have more than half a made up sachet per day (equivalent of two x yoghurt tubs). Any more would be "greedy" I feel!
I'd say the Hartley's sugar free ones are the best way to go.
Didn't even know you could have those in Attack. I think I'll go get some tonight!
I'm not a big fan of yoghurt, so this will do me fine instead of yoghurt