You sounds like you want to progress quickly before your trip. This is great!
I think the best way to do this would be to actually go take a private lesson if you can afford to do so. If not private, then a good group lesson. Tell the instructor what you want to achieve and I think you'll be surprised at your progress.
Take a lesson as soon as possible, then have another trip out to practice what you learned before you go with your friends or even take a second lesson, ideally from the same instructor provide you liked him and got value out of it. That said, if you didn't get value out of it I'd talk to the ski school and ask for a comped lesson with someone else.