This is what is going to happen.
You will arrive and your friend will be very pleased that someone turned up who she invited. She might introduce you to other boys (its the "done" thing) and everyone will be REALLY REALLY nice to you.
At some point it is highly likely that someone will ask you if you want a free home bible study. Be ready for this question and say no. If you say yes, it will not be the girl who will visit you, it will always be men (men teach men, women teach women).
Everyone sits down. Then there is a song (everyone stands to sing) and a prayer. Then everyone sits down and listens to an extremely sombre and boring talk. This lasts about 30 or 45 mins I think. Then they pass around the bread and wine and every person passes the bread or wine to the person next to them and its likely that you will not see ANYONE eat any bread or drink any wine because they don't allow it.
Then, another song and another prayer. Then you can go home.