Don't worry. The sharks at Elphinstone are familiar with these black, silver bottled creatures. They may come close, very close, very very close, but rarely bite.
The first rule is: Don't panic!
Stay with your group, stay upright in the water, keep an eye on them and never, never try to swim away. Regardless how fast you can swim, they will be faster.
You may brief your budy to stay behind you, so he can gently tip your shoulder, when there is something coming from behind...
Always follow the briefing your guide will give you. They know the site as they are doing this for a living.
It is likely they will apply an exit procedure where, at safety stop, the guide will point at you when it is your turn to surface. Follow that. Purpose is to not have a bulk of paddling divers hanging at the surface.
Don't worry to not get on the zodiac quickly enough: the guys will pull you out with your full gear on, including weights if you are struggling or if a little hurry is appropriate.
Note that the drop off is worth some time as well, so not only the sharks are a good reason to go there.
All in all a great experience.