Hey,
Tough but i guess there are two things you can do. You can either just do the black coffee route and a bar and explain or you can push food round your plate. I found both a bit of a pain. I didn't like to have to explain myself to anyone and have to justify my choice to be on the plan. I found that folk were fasinated and that made them more nosy than they needed to be. I didn't particularly like that. I have, in the past, used the old, I have a headache and left. Not really good for sociallising but at an early stage it was how I coped. I am back on plan again too and I was supposed to be going out for dinner tonight with friends. i have decided not to meet them until after they have eaten as I know that I will just want to eat with them. Hard to miss out but I know myself too well.
The push some food about the plate may well be a good option, a little rice, a little curry, smash up a popadom and play with it in your hands like you are going to eat it. Depends how good you are at just playing with it and not eating it!!! I would fail miserably at the moment.
Stick to the plan if you can, hard I know, not doing so well at it myself this past couple of weeks but we both know it works if we work with it.
Good luck.