Welcome to the island.
There is a dive shop in Gander. As I understand it it operates out of a guys basement and all you have to do is catch him at home. He'd probably be a good start to diving in Central. Dive shops are always a good place to start.
If you have problems locating the shop and possibly dive club in Gander you could ask one of the guys at a dive shop in St. John's and they could probably steer you in the right direction.
St. John's and area has 3 full time dive shops. Dive Newfounland (with a new club just starting), The Dive Shop, and Ocean Quest who have a lodge, dive tour boat, training pool as well as the shop. Anyone at these shops should be fairly knowledgable. You could also try PSE (Pretty Safe Enterprises) a friend and ACUC, PADI, DAN, Red Cross...........instructor. PSE is on the net as are 2 of the shops.
Good luck and Happy diving