This might be a dumb question
It is not.
in the property below, will there ever be a situation where just getting it will cause an exception?
Possibly, yes. For example, another thread could abort your thread while it was in the middle of fetching that property; that would appear to be an exception thrown by the property getter. Or, you could run out of stack space right at the moment where the property is called, and an out-of-stack exception could be thrown. Or, when you call the property for the first time, the jitter might start up and try to allocate virtual memory for the generated code, but you are all out of virtual address space, so an out of memory exception could be thrown.
Those are all extraordinarily unlikely, but they are all possible. You asked if there would ever be such a situation, not if it was likely.
If I hadn’t set BatchValuation yet, will it just set value to null, or will it cause an exception?
Neither; it will default to false. Booleans are not nullable.