Hey Byron
I did a write-up some time ago in WP on the Simply The Best trip which I did with Emperor Divers. I'm not familiar thought with the Blue Horizon.
For wide-angle and possible big fish encounters it's a very good trip. If you haven't dived the Red Sea before, you are not going to be disappointed - well, I would hope not anyway!
Depending on what photo gear you have, I'd suggest you don't really need any macro gear. if you use a DX format, it's Tokina 10-17 country. If FX, a Sigma 15mm. If you are lucky, something maybe a little less wide for the Big Fish. But, I have to say, everytime the dive guide suggested hanging out in the blue just in case...... nothing. It's a good place for the shots of divers against fan corals, sticky-out bits of colourful soft corals, shots up the wall showing variations in blue to the surface.
In June the water should be getting to be a nice, toasty temperature and I would suggest a 3mm suit should be enough.
I don't know how Blue Horizon operate but I'd expect most dives to be drifts with a pick-up - and sometimes drop-off - by RIB. A safety sausage is essential (just in case).
Enjoy!