I eat before I go if possible otherwise I tend to rush and do the shop quickly, often without much thought. I usually go with a weekly shopping list for SW stuff so I know what I am having ahead of time, but usually if I go from work hungry because things are going on, I've not prepared and I am then taking the chance that I'll cave.
But like you I tend to eat something in the car while reading a new mag lol! I go for 5 cheese triangles if I have an HEA left of fruit but I have been known to snarf down a packet of syn free turkey slices on a red day - on their own. I am gross! LOL xxx