I feel your pain, Bladebabe, I'm exactly the same. We're going away in for 2 weeks this year instead of the usual one week and I'm dreading the thought of 2 weeks of bad sleep!
Anti-histamines that make you drowsy are a good choice. I usually have one close to hand on the bedside table so I know that if I'm still not sleeping hours after going to bed, at least that will give me a few hours so I can function the next day.
I saw something on telly not that long ago, saying that most people don't sleep so well in a strange bed as they do in their normal one. Something to do with our fight or flight reactions?
Sounds silly, but I'm honestly thinking of packing my clock when I go away, as I spend most of my sleepless nights wondering what the time is. Watch is too small to read in the dark and the light on my phone would disturb OH if I used that to check the time.