I have been to Grand Cayman diving 14 times. I love the East End Diving and have dove with Ocean Frontiers many times and they are a great dive operator. I have stayed at the Reef Resort and love it. If you want to dive the East End, I suggest this combo.
However, I think you should think about this. East End diving is more advanced diving. And conditions are rougher than other locations. For new divers, I suggest you start on the West Wall. Conditions are always smooth water and no current. Great diving there too. Once you have gotten comfortable with wall diving and deep diving, then you will be ready for either the North Wall or the East End diving.
I have been diving 36 years, but my wife is just now getting certified. I am taking her to Grand Cayman Sept 21 and we are diving the west side. I want her to get comfortable with the perfect conditions she will encounter there. Next year, I will take her to the East End, or Little Cayman or Cozumel. But not as a brand new diver.
Besides, the west side has soooooooo many great shore dives. You can do two boat dives in the morning and then do inexpensive, but great shore dives in the afternoon or evening. I really suggest you consider the west side. And if you want to dive the East side later in your trip, it's just a 25 mile drive away. I've done that several times - stay in the west but go over and do the east on a day trip. Good luck.