If it's too tricky to do the Syn limit and counting them and stuff why not just set yourself some basic rules as to what you will and will not let yourself have? eg tell yourself you'll order grilled meat and veg with no sauce and not have dessert, but you'll let yourself have a few drinks. (or whatever combination works best for you) You can set yourself a rule for the drinks too, eg no more than 1 bottle of wine or that you will only drink spirits with diet mixer or something?
I do it this way every week to give myself a 'day off'. I have a moderately healthy meal on Saturdays but let myself have whatever wine I want with it.
This w/e I've got a wedding, so inevitably I have no control over what Ill be offered at the meal/buffet and some drinks will be quaffed. But basically I set myself the rule that I let myself eat whatever is in front of me that is healthy - so I'll eat the fat-free bit of meat and the veg but I wont put on any sauce/butter on. I wont eat bread on the side or dessert (unless its fruit). I'll give my piece of the cake to the O/H. But I will let myself have a few glasses of wine - but Ill intersperse each drink with a glass of sparkling water or whatever (at least until later in the evening
) At the buffet it's even harder as it's always pretty unhealthy stuff, but Ill do my best. I might also take a bag of fruit and healthy bits n bobs with me to snack on if I need to.
You could also take some stuff with you to cover you for the first day until night time but make it part of a fun day out - then you've replaced at least two out of three meals that day with something SW friendly - pack yourself a healthy interesting picnic to take with you, it doesn't have to be d*et-style, you can make it a bit of a fun picnic, make stuff you wouldn't usually have, spicy lentil salads or spicy grilled meat, homemade free spicy hummus or a million other things. Make a massive box of yummy SW friendly food that you can picnic or snack on until tea time. Even if you only manage to make Day 1 healthy it's a massive improvement on pigging out for the whole w/e!
But at the end of the day you've done amazingly well to be so close to target - one weekend off is not the end of the world, we all have to have a life as well! Even if you out a pound on it'll be gone again within a week! Whatever you decide to do, make sure you have fun doing it!
Have a good weekend and well done on what you've achieved!!! x