Yeah we found going out hard for a while when she was throwing food. We've only just started going out a lot again. I just used to take things I knew she would eat, cheese, fruit etc and if she didn't eat much at lunch then I would make up for it later with afternoon tea or dinner.
My dd has only just stopped throwing food recently, it's so much better!!!
It's a messy business alright, my DH really had to exercise all his patience, it drives him mad, but they are babies and I just say to him, no one has ever thought babies are neat eaters.