We took all our gear and camera when we stayed at La Toc (2x). There rental equipment across the resorts appears to be in good shape. I didn't hear any complaints from those that used it. If you search on Sandals La Toc on the forums you will get many links which are too many to summarize here. They will pertain to dive times, sites, boats, procedures, etc.
They don't do any gear storage so you will end up bringing it back to your room.
You may have to travel in there vans to Castries where they depart. They may have divers from Halcyon or Grande on the boat(s).
Make sure to sign up every day early (or immediately after the last dive) as the boat can fill up.
The resorts in general are not geared toward divers but couples and especially honeymooners. You will have a mix of experience on their dives.
Water and air temps vary over the year. August is flippin hot topside and water was high 80's to 90F at shallower sites.
If their diving is not for you then you can always go with an outside dive OP for a price. We have done that at some Sandals resorts and others not. It's hard to pass up the included price. Other dive OPs will generally dive the same sites but you may get more bottom time with other ops. The last time I was there I have to say that the diving was pretty good at sites to the south of the island (west side).
If you have other or specific questions I will try to answer them.
