Hi YoYo,
I love to lift. I do it in a gym with dumbells, barbells, levers, and cables. (It isn't however an iron pit.) However, there were a lot of steps that I took before I ever reached this point. Its all about taking steps that make you comfortable but keep moving forward. Once you master what you have been exposed to it is time for a new challenge that excites you. If you want to take the BodyPump, take it. You will certainly learn something new that will carry over to the next goal for yourself.
I do agree with Nelie in that form is really important in lifting. A class could be good in that you can watch an instructor's form, there should also be a mirror so you can see your own. Hopefully the instructor may also be skilled in correcting the participants' form as well. I wouldn't rely upon them though.
After your first class make a note of the different exercises that were executed. Google them for several videos for correct form and then practice.
You may also want to hire a personal trainer for a few sessions to help you feel comfortable in the free weight area.
There are so many tools available toward fitness and all the steps that take you there will count. Just go with what is available and interests you at that time and keep moving along.
As an aside, I've never taken a BodyPump class. (cringe) I just don't like classes in general. Too many weird experiences with the "find a buddy" classes from the past.
I kind of like to set my own goals instead of following someone else's lead. I did just meet someone this afternoon who takes one three times a week and loves it. Physically, she looks pretty fit. It's all about doing what you love.