Right I get what you mean now, ok personally if I were going out which is a rare occasion for me I would eat my full quota of snax and shakes and meal, seeing as its a rare occasion id just go out and enjoy myself because hey we can't be good 100% of the time and we need enjoyment in life too, it may slow my weight loss down for that week but aslong as I got back to it the following day I wouldn't worry about that too much!
If I were looking at having a glass of wine at home with an evening meal I would look at how many calories I would need, I have 2 snax and 100 cals worth of milk for cups of T.
Say a glass of wine is 150 cals I would generate a larger calorie alowence by doing some exercise but if I couldn't do that I would possibly save 75 cals from my main meal and 75 cals from my snax, I think white wine has more calories than a rosey or red, and I probably limit this to a couple of times a week.
Hope that makes sense x