Relax, it's going to be fun. The night dive will be amazing....unless you shine your light in someone's eyes and they turn off your air. On the upside, if someone blinds you with their death ray 10,000,000 lumen submersible air raid light...you get to turn off their air. The amount of time until it is turned back on is directly realated to the brightness of their light. The general rule is that once the yellow dots in your eyes go away....its time to turn their air back on....if necessary.
BHB would be a good stop to work on buoyancy. As a new diver it will take several dives to get your buoyancy under control. Relax, don't fight it, use little bursts of air in your BC and fine tune with your lungs.
If you have not done a back roll before, again, relax and let the tank do the work. Hold your reg and mask with one hand, mask strap with the other, lean back and gravity will do the rest. Gently kick away from the boat as soon as you splash.
The main thing is to not get frustrated if you aren't as trimmed out and graceful as divers with 100's of dives. There is a learning curve and it is pretty quick. Watch other divers, find a comfortable position to not use your arms, and listen to your instructor, the dive master, and your buddy. If you catch yourself turkey diving(flapping your arms like a turkey) stop.
Watch your air, and if you need help, ask.
Good luck, safe travels,
Jay