Go to the tea party and have a good time. If you have a cookie so what, it is not the end of the world. But take your celery sticks. If people have a problem with it then it gives you a built in reason to avoid the next one and not feel guilty about it.
Take you mug and sit and talk with friends. I assume that is why you are going. Just try and enjoy yourself and who knows...you might even like it.