There are several clubs and several diving shops/schools. Apart from the above mentioned there is Q-Dive, located near the gold souq (on the opposite side of Grand Hamad in a small square), world marine centre next to the Museum (when does it re-open?) and another near B-ring somewhere.

Perhaps the best/cheapest option is the Doha-Sub-Aqua-Club, although this is a BSAC organisation the social aspects are unmatched and they are the most regular divers. Conversion from PADI to BSAC is simpe and there are many that have done it. The DSAC is not just a group of "British" expats.

There is also an Al-Khor PADI club.

Still one of the best options is fly to Musadan/Oman for a dive!