What if I'm not comfortable, will that make my sleep study inaccurate?

Yes. It certainly can. It's one of the most common causes of faulty, inaccurate sleep studies.
No one is. No one will be as comfortable as at home, but most sleep centers are trying to make there rooms seem like nice hotel rooms. It is just a snapshot of a few hours of time. If you get at least 4 hours of sleep and get into a rem cycle, the study should be close enough to give a diagnosis of your condition.