Firstly, well done Merope. The first week can be tough, but it will get easier. Secondly, don’t stress about being away. It perhaps could have happened at a better time, but regardless, you should go away and just enjoy your holiday. The secret to being able to stay the course with the BSD, is accepting that life happens and we need to adapt our approach accordingly.
So, relax and just enjoy your holiday, while looking to stick with the BSD principles as closely as you can. That means ordering meals that are light on carbs, so no potatoes, rice, bread, pasta,etc., try to have meals that have a protein source and either veggies or salad. Limit fruit and if you can bear to, try not to give in to desserts (too often!). Also try not to give in to biscuits, cakes, confectionary and so on. Have the occasional glass of wine or shot of vodka if you fancy it. Make sure you drink plenty of water, etc to keep hydration up. I find this the biggest problem when travelling.
You are only going to be away for 5 days, so if you stick with the principles, you should find you gain very little (if any) in that time. Then when you are back, think of it as a brand new start and begin again, strictly sticking with the 800 cals.
Best of luck with your endeavour and look forward to reading of your progress.