Determine when no liscense is available using COM (python)

I am using a modified version of the script I found here to run TestComplete and TestExecute, related code follows:

from win32com.client import Dispatch
import pywintypes

...

        try:
            self.test_complete = Dispatch("TestExecute.TestExecuteApplication")
        except pywintypes.com_error:
            try:
                self.test_complete = Dispatch("TestComplete.TestCompleteApplication")
            except pywintypes.com_error:
                sys.exit("TestComplete/TestExecute not found")

However I have an issue when there are no avaiable licenses. After calling Dispatch a dialog pops up (image below) and the Dispatch call blocks.

This breaks all the automation I've been trying to do with TC/TE, and I'm looking for a way to determine before calling the Dispatch that no liscenses are avaiable.

Thanks