You have a lot going on. I always have anxiety prior to a holiday

Valium will help, I used it - 5mg - for many years as necessary : the night B4 event that I couldn't get out of. That way I knew that I could take another during the day but never required it.
Anxiety can be caused by hormone upheaval and may take a while to settle once you take HRT so you may require an anti-anxiety or betablocka until the anxiety eases. Then you can decide whether to try without and let any HRT do it's work.
We aren't menopausal until at least 12 months without a period. So if you get 1 you have to start counting from that day

. Perimenopause can throw up some awful symptoms

........ and breath. Half a day at a time. What's the worst if you don't to on the holiday but take some time out? I used to think that I was spoiling our holidays but in fact, I am not responsible for how others react. Or you could get there and rest, if the others want to go out and about then let them?