I am guessing that (in the US) it would not be an easy thing to be allowed to see an autopsy unless you were a medical employee, law enforcement person, or medical student of some kind.
HIPAA (Health Insurance Portability and Accountability Act of 1996) rules generally place privacy and security rules on access to information about people's (living and dead) health conditions. The easiest way for a busy management to enforce these kinds of restrictions would be a general denial of access to things like this, unless there is a good obvious reason (medial, law enforcement, teaching) for an exception.
There are also potential contamination issues, including from aerosols if a power saw is used to get through the skull.
Administrators would not want responsibility for this.
Even getting access to preserved humans brains (used in teaching neuroanatomy) is not entirely simple.
I often work in hospital morgues, removing corneas from dead people. Most of these kinds of morgues are not set-up for an audience.
In movies I have seen OR's, probably in medical schools, where an audience can be seated separated by a glass wall. This might be the most likely path, get a pass to tag along with a class event.
If you are queasy about viewing dead people, you could do things to mitigate that beforehand:
Gradually exposing yourself to increasingly dire situations might reduce your negative reactions. This can be done by watching or doing dissections on animals (in the proper circumstances, such as in a class) before viewing humans, or other things like that.