Hi Charlie!
A couple of things, not sure if they will help or not!
Life is going to happen, when we all get to this magical goal we are all aiming for, life is still going to happen, and it is how we deal with it that will make the difference between staying at goal and gaining all the weight back and more. Did you drink last weekend, and have a MacDonald's? yes you did, did you continue doing that during the week, no you didn't, you got straight back onto SW...you won that week! Did you drink this weekend, and eat crisps and ice cream, yes you did, but you are going group tonight and facing the music, good or bad, you won again.
Drink, chocolate, crisps, takeaways, chocolate etc are not going to go away, we all (and I say this to you and myself!) have to accept that it's not the eating and drinking one offs that are the issue, it is the continuing to do it 'because we screwed up and we might as well continue to eat and drink crap, because we have failed, and we are worthless, and we are supposed to be fat/overweight/chubby......' . When we fall over, we need get up and dust ourselves and get on with it, and not wallow in it like a elephant in a mud bath!
Everyone is different, I know personally that if I promise myself I will only have a couple of drinks that it isn't going to happen most nights out so I rarely drink now, but if I was I go for something with the least damage so for me that is vodka and diet coke. And we all know the best hangover cure is crap food, so what about making a deal with yourself (if that would work), OK you can drink, but you have to go for a walk to blow out the hangover on Sunday....or you can eat, but you can't do the drinking? Or plan your hangover food out before you are hungover, so you mitigate the damage, have a fry up ready to go, it just needs to be put under the grill, or have some crisps synned out?
I am not sure if any of that helps!