I recently pulled low voltage into a new home. It was my mothers house and it has been difficult dealing with a commercial manufacturer. They had me pull my stuff before the electricians. So I am concerned about the electricians screwing things up. So I am looking for an idea to prevent possible emi if/when they cross my wires etc. Is there some type of shielding material (wood, metal, plastic etc) that I could put between the high voltage and the low voltage???

EMI from a high voltage line is generally not a problem unless the two lines are in close proximity for a significant distance. If there is a problem, try to separate the wires as much as possible. Using shielded wire, or running the low voltage in a grounded metal conduit where it's near the high voltage should also help.

The problem is all the wire is already pulled, I am now waiting on the elctricians to pull their wire. I have told them not to pull the wire into the same cavity in the wall. I was just wondering if I could do something if I see a bunch of High voltage crossing my wire. They know not to run parallel with it.

Just crossing is not likely to cause a problem. Make any crossings as close to a right angle as possible.

Can you test the circuits before the drywall is done?