If you turn off Location services, you indeed turn off the GPS, mostly. The radio may or may not be on, I'm not sure, but the iPad will not collect location information or provide it to apps)
First, if your location is reasonably accurate, then you are using the GPS. The wi-fi and cellular triangular methods are good enough to tell where you are within a few blocks. GPS with a good signal, should get down to 15 meters.
To test if it is working without internet or cellular you can turn off the Wi-Fi and Cellular data in Settings. Be sure to turn off Cellular, because even without a SIM the iPad can use towers to triangulate it's position. (Don't use AirPlane Mode, apparently it turns off the GPS as well, maybe, my tests were inconclusive)
Of course, this means Maps and other apps that depend on the internet for data won't work properly, since they can't get map data, and unlike the iPhone, the iPad does not come with a compass app.
It's not easy to find location data using the native apps. It kind of possible using Photos and the Camera, but not satisfactory in terms of accuracy, and it requires a lot of playing around. So I recommend a visit to the App Store and a quick purchase.
The only app I have on my iPad that lets me 'easily' see position data is Theodolite HD, this is a survey app that uses the camera and other sensors to emulate a Surveyor's tools. Very nice; but it costs a little (3.99) and is overkill if you just want your position. So I recommend you look for a free compass app that gives co-ordinates and GPS accuracy information (similar to the one for the iPhone). There are dozens.
I did a quick search and downloaded the first few (free) compass apps that had decent ratings. Compass Commander Lite is busier than I like but should do the job.
Or you could buy one of the Map apps that include map data. There are quite a few of these, the cheapest ranging between 20 to 30 dollars. That may seem like a lot, but these easily take the place of dedicated car navigation systems, at a fraction of the cost, and far easier to update. I use one of the CoPilot apps.
(Just checked, and there is a new CoPilot GPS - Free Offline Maps app. With in-app purchases. I haven't tried it, but it should be good enough for your testing purposes.)
Hold in mind that the iPad uses internet and cellular services to improve the speed and accuracy of location services (AGPS). With these turned off the GPS will take a bit longer to find itself and may not be quite as accurate.
