Most likely, it is a service with readings and possibly a homily, followed by an examination of conscience and then individual confessions.
Sometimes these services are abused and general absolution is given. General absolution is where the priest absolves the entire community at once. This type of absolution is reserved for dire circumstances (such as when an airplane is going down). Then if there are any survivors, they must go to individual confession as soon as possible.
Enjoy the service if you go. It can be a very beautiful way to remember our sinfulness during Lent (if it is not abused). Though you will not be able to go to individual confession until you officially enter the Church, you can still meditate on the readings, homily, and examination of conscience.
Congratulations on your approaching entrance into the Church!