At first glance a Krav Maga class looks very imitating. Taking a peek though a window you might see some practitioners with high energy and skills striking hard on pads or even on each other. The pressure tests are designed around reality based training, and can also cause anxiety. This is why the majority of my online clients are people who want to join a regular Krav Maga club but want to walk into that class with a solid foundation and understanding of the style.
Having the advantage of some background knowledge in the theory and able to hold your stance and use basic movements and techniques will mean that your learning experience on the mats is much better.