Yours is not an unusual story. It can indeed be frustrating!
I figured that I had a 50% cancellation rate when I was doing my PPL. Mostly weather-related (I had the same instructor throughout, which was great). It's not that the weather is not suitable at all for flying - its just not suitable for what your instructor wants to teach you. You can wait months to go solo because the weather is not perfect. Cross-country is another hurdle weather-wise, as is the skills test.
Once you have your PPL you'll find that the weather doesn't restrict you to the same extent. If you are hiring they will usually let you have the aircraft for a longer period if you are delayed waiting for the weather to clear.
One thing though - if the wind is out of limits you can forget it. The wind doesn't change very much during the day.
Yes, double book your lessons, and do it as far in advance as possible. Your school will understand. You can always cancel the second one, but it's likely you need to catch up anyway.
Annual leave is also a good time to do a lot of flying. I was out of work for some months and was able to use the time to pass my PPL.
If going to the US don't do your whole PPL there - maybe just the first 30 hours or so. Flying here is very different.