I won't lie, there is crying at sleep school, but there was crying at home for us anyway! The place I went to used responsive settling and they helped come up with something I was comfortable with, and that was appropriate for the age of my baby.
I suggest you give them a call to find out if you're willing to use their techniques.
We had five nights at sleep school. The first day DH and I spent about three hours with a nurse doing an entry interview where she went through his typical day, his development, what we tried, how we felt. She watched him feed and then she and another nurse took it in turns to try to settle DS to sleep in a cot.
DS and I both cried. It was a huge change for him, and we were both massively overtired which made it even harder. However, I was at the end of my tether so we persisted.
The idea was to listen to the noises DS was making to see if he was trying to calm himself down. If he was calming himself, then we'd leave him. If he was getting more upset, we would go in and do the minimum required to calm him. That's why it was called responsive settling - we responded to his cues, rather than leaving him a set amount of time. They had infrared cameras in the room so they could show you that even though DS sounded upset, he was actually lying calmly and sucking on his hands.
I found it really helpful as they helped me understand DS's cues more clearly. I thought he was hungry but he was usually tired instead. I also discovered that he hated being touched when overtired and wouldn't respond at all the patting or shushing, which is all anyone ever suggested to me. It was also good when they all tried to calm him down and failed - I discovered that it wasn't just that I was a bad mother if six expert nurses couldn't settle him. That gave me 'permission' to just give up if it was too much and try again later.
It was also fabulous to speak to other mothers who understood the torture of a bad sleeper. While I was there, most of the mothers were there with their second babies - because their first babies all just slept! Remember that a lot of people just haven't experienced how bad at sleeping some babies can be.
And please don't think it's a failure to go to sleep school. It's okay to have a problem and seek professional advice to solve it. It would be more of a failure to drive yourself past breaking point