For a 97 MGF, you need either the factory T4 unit or the Pscan, the typical OBD2 units you find on ebay etc, wont work on your car as it isn't OBD2 compliant.
Good luck finding a T4, so the Pscan is your best bet.
The Pscan is an excellent piece of kit.
A huge thank you to Philip for developing it!
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"