Tracey, I know how you feel. Everyone tells me what great discipline I have, but they forget that I live alone and could easily eat half the bag of tortilla chips and no one would ever know! Sometimes I really really want to.
And speaking of slipping up, Friday night, my boyfriend was doing a live taping of his cooking show, so him and a couple other chefs were making food and serving it to the crowd as they came and went. Well, I ate dinner before I went not realizing what I was getting into. I was fed one dish after another until I thought I was going to pop. Then him and I went out with some friends after where I proceeded to have two beers, appetizers, and stayed up way too late. Woke up around 7, and I could hear the wind whipping rain at the windows and would have loved nothing more than to roll over and go back to bed. But I waited for the rain to quit, then made myself get up and go for that early morning run, and I've been very carefully counting my calories and working in extra exercise when I can.
I think most of us here on fitday understand the struggle it is to stay on track. Don't beat yourself up too much when you take breaks, but know there's a community of support here to help you get back on wagon.