I think this is why a lot of people go to the same resort and hotel every year, it is a known quantity and they feel safe.
I always feel a little bit apprehensive before a holiday, but i am better than DH, who's guts go on overdrive and he is in and out of the loo before we set off!
I cope by making lists ahead of time, planning what jobs need to be done before we go e.g. locking windows, cat to cattery; packing a small first aid kit and some meds like painkillers and anti diarrhoea tabs, pack clothes to suit all types of weather and so on. I don't like to be caught out, during the perimenopause when periods were irregular, I used to pack loads of pads and tampons in case shops were shut or difficult to get to at certain points during the holiday especially if on an excursion.
I find it helps to allay any fears such as "did I lock the door" and "have we got the passports" by showing DH that I have all the relevant documentation before we leave the house, and also if he watches me lock the door, we both know that it has been done.
Would it help you to take photos of loved ones with you, or speak with them on the phone or by email at intervals through the holiday? If there is someone checking your home, have a word with them to put your mind at rest that your home is fine? Take a little mascot/soft toy with you as a reminder of home. Before the holiday, research the trips and activities that are available and decide what you would like to do, it gives you something pleasurable to look forward to and focus on particularly if something you couldn't do at home. Then the actual going away bit is a means to an end. Keep yourself occupied at the airport and on the flight, which helps the time pass quickly. There's nothing worse than sitting worrying with another hour to go!