A cellular iPad uses three methods to determine your location. In order of best to worst for accuracy they are:
GPS (AGPS when available)
Cellular tower triangulation
Wi-Fi network triangulation.
AGPS (Assisted GPS) will use both cellular and wi-fi to increase the accuracy and speed of the basic GPS system, but will still work with neither available.
Cellular triangulation does not require you to actually have a usable cell signal from your carrier. Any towers in range that are compatible with your device will be detected. Your device will use a database of known towers to guesstimate your position. This database is downloaded periodically and usually includes a 30 to 50 mile radius of your current position. As long as you've had an internet connection in the recent past, you iPad can probably guess your location to within a few miles. The more cell towers (the more urban the area) the more accurate it will tend to be.
Wi-Fi, does not require a current connection, only that the wi-fi radio be turned on. Like the tower triangulation it depends on a database of known wi-fi networks to estimate your location. Provided you are in range of enough known networks it can be more accurate than the towers, since wi-fi has a smaller physical range. You have to be within a few hundred meters to get a signal. However, the accuracy of the database is less reliable than the cell towers, so you occasionally see some odd results when this is your only location resource (as it is in wi-fi only iPads).
Combine all of these, and assuming you don't turn off any of the radios off, the iPad almost always has a fair idea of where you are, within a mile or two at the worst. Usually much better. Unless something goes seriously wrong your boss is going to know you were at least in the general area of your assignment.
But: If in doubt, fire up the Maps app. Tap on the arrow at the bottom left of the screen (so the icon is a gray square with the arrow in the middle) and the map will center on where it thinks you are (blue dot). If it is surrounded with a faint blue circle, that is the iPad's estimate of how accurate the location data is. It's saying, it thinks you are the blue dot, but you may be anywhere in the faint blue circle. If you can't see the blue circle, just zoom in some more.
Mine currently shows me in my neighbors house, though the circle admits I might be next door to them.