I can't seem to take divots!

[Paul Diehl]

I an a left hander who has been playing for three months. I have no problems off the tee (using a 3 iron I hit straight up to 200 yds). On the fairway though I cannot seem to get under the ball and never take a divot even with my short irons. I get about 60% of sweet shots but the remainder I top. My next pro lesson is two weeks away any suggestions to tide me over would be very much appreciated.
Paul.