I will never understand why people are so nervous about communicating with their child's teacher?! What's so hard about writing a letter or, better yet, phoning a teacher -- someone who spends almost all of your child's waking hours with them? They are people like you and I.
Just explain the situation, ask what you and your child can do to make the transition with homework, etc. so that it is the least stressful for your child. Don't wait until the last minute. A teacher, I would imagine, would like as much advance preparation time as possible.
The only thing I can figure that must be making people nervous is that they feel a little guilty about taking their child out of school for a vacation. I have my own viewpoints on that one -- that being that it's just not worth it. Depending on the grade level, it can be very stressful on the child in making up work either before the vacation, during, or after returning from the trip.
And I really don't buy into this "my child is learning more on their vacation than they ever will learn in school." Vacation is vacation -- by virture of the meaning of the word -- a break from your work/school schedule. Just as you tell your boss ahead of time in the work world, and arrange your work duties for your absence, you need to address school the same way.
Go ahead and call/write the teacher(s) and just deal with it. There should be no apprehension in approaching them -- believe me, I'm sure they're quite used to it (and some of them deal with it too, if they're parents).
Have fun!