Answer amain, wait until he begins to drink the wine, and then you can begin eating. Sometimes a person will make a kiddush specifically for invited guests and relatives. There are any number of reasons someone might do this. It's nothing to be offended about. If someone announces a kiddush, it usually means it's open for everyone, but pay close attention to the announcement anyway, just in case.
Some synagogues have a kiddush every week, arranged by the members.
Sometimes the kiddush is donated by an individual. The offering of free food to the public is an act that makes people feel good, so this is counted as a merit for the soul of the deceased. During the kiddush is a great time to mingle. Most especially, get to know the Rabbi. If you are there alone, don't worry about being introduced.