Study the fights. Watch some videos. Don't say you are new. Then, you won't have this problem.

I've seen people, right before the last boss in Turn 1, or 2, that they declare they are new, but we're so far into the dungeon that they are not going to be kicked. In fact, they are usually helped by the group. The fight strategy is explained and most of the time, about 98%, the run is smooth.