You will know what to do. I paid $150 for birthing classes and it was a waste.
I took them only because it was free, but after the fact realized everything stated was common sense and they didn't give any special advice.
We didn't take them with our first because my husband was in night school and it didn't work out. As mentioned above the l&d nurse's are pros and walk you through everything. I wouldn't stress if you can't attend them.
I don't think the are a necessity but are nice to do. They teach you some breathing exercises and definitely prepare you for what to expect. GREAT for your partner. my husband was really clueless and it was helpful for him. PLUS, bonus!! /they taught him how to give me a massage to reduce stress--- loved that! But in truth, when you get to the hospital, the labor and delivery nurses take over and guide you through everything. So, take the class if you can but don't worry if you can't. good luck
I did not attend any classes, if I had no clue about what to expect I probably would have.