I might get into trouble for saying this but there is a diet you can follow to lose a stone in a week.
It's meant to be for people who need to quickly lose weight before surgery and has been recommended by doctors for this reason (although is obviously only meant to be followed for a week).
I can't remember the exact diet (you can Google it) but I do remember that the lunch option was unlimited fruit each day. The breakfasts were depressing like one piece of dry toast or one boiled egg, and then the dinner was pretty much a grilled meat (steak or chicken) with unlimited veg (no sauce).
I edited this diet to make my own less depressing version which I thought I could stick to - for instead of having the depressing breakfast and the unlimited fruit for lunch, I just merged the two and had unlimited fruit for both. I eat a lot out of habit than because I'm hungry (I mean even when I'm not hungry I like to pick at stuff and have stuff to snack on) so this worked brilliantly for me because I could still pick.
Then, for dinner I'd eat either a chicken salad (but I seasoned the chicken to make it tasty and used loads of veg or added an egg to make it filling) or grilled chicken breast and loads of brocolli, carrots, beans etc. (I don't eat beef so I didn't want to do that part of the diet, and I'd rather eat nothing than eat a piece of dry toast in the morning!)
Because I was eating so much fruit and veg I was not only full but I felt amazing! I'd wake up each morning with loads of energy and keep it up throughout the day.
I started going for an hour long bike ride each day (this was a coincidence - I just started a new job which id cycle to) and I started walking more - taking my dogs for long walks each day. So I did increase my exercise but only a little and it was relaxing exercise rather than a gruelling gym workout (which I'd never have stuck to).
After 5 days I went shopping and I'd dropped a dress size, I had countless compliments and shocked comments about how I'd lost the weight so fast and how I looked not only slimmer but healthier. Clothes fit that I'd not worn for years.
After two weeks of doing this strictly I eased up loads, reintroduced the odd alcoholic drink, occasional rice/quinoa/sweet potatoes, even the odd pizza! Basically I relaxed loads but kept up with the loads of fruit and veg as the thing I ate most of, and I kept up the bike riding and walking too. If I have a bad craving for something I'll have it, but I never use anything ready made and will always make my own food fresh which I think helps a lot too - no sauces or ready meals which is where all the sugar is hidden. So the weight just never came back.
I'd really recommend you to try this because 1) it works so quickly that it gives you the encouragement to go on! 2) it's easy to do, and you don't need to be too strict 3) the weight will drop off and you'll be confident enough to go on your holiday! 4) a relaxing holiday alongside a new healthy eating plan might be just what you need to cheer yourself up!
Sorry if this isn't what you were looking for (I know you were asking whether you should go on the holiday) but I just coildnt help but post this because I did this diet because I was in a similar situation to you - comfort eating due to dperession and gaining weight which was making me feel even worse - and this diet combined with the gentle exercise really worked, made me feel great, confident and happier too. So maybe it could do the same for you 