Personal hotspot feature doesn't appear.
My ISP has enabled the wireless sharing feature, but the personal hotspot feature doesn't appear in my settings.
iPad (3rd gen) Wi-Fi + Cellular, iOS 6.0.1
First thing to try is a reboot of your device. Press and hold the Home and Sleep buttons simultaneously ignoring the red slider until the Apple logo appears. Let go of the buttons and let the device restart. See if that fixes your problem.
Perhaps it will appear then.