There are a couple shops that have guides and there are private guides. The site is very doable with just a buddy, no need for a guide, however, going the first time I always recommend a guide. They know the area very well, and can give you a lot of tips, tricks, and other info about diving the site.
Also there is this group who posts here, and a lot of other groups locally that dive the bridge. SB has been a fantastic resource for me over the years finding buddies and exploring new places to dive. Good luck!
Is this dive group open for visitors and possible to join as a member?