While I'd like to say yes (there's a part of me that aspires to be the domestic goddess) alas, I have to say I'm not that organised. I'll generally stop and buy some cold chicken and salad along the way.For me it makes it a more relaxed and enjoyable outing.
We don't have picnics a lot...which is surprising considering the amount of time we spend travelling! When we are travelling I will often buy a few salad ingredients and ham and bread and everyone has sandwiches. Or I will get "snack" type stuff for me. We do a fair bit of fish and chips in a park. Or macdonalds...because they have good coffee!