The road leading to the castle opens 30 minutes before an event starts - there is a sign explaining this. We got there 35 minutes early, drove around the block once and we were in. Buy your tickets in advance - there are minimums for tours to go on.
Tour guide was excellent and used information gleaned from historians and people who used to live and work there.
You only get to see some of the castle as they live in the other part. Also, there are some stairs, so be prepared to walk and take stairs. Nothing too strenuous. My senior citizen parents, I and my 20 year old went.