I go to the Cape Canaveral / Cocoa Beach area a few times a year. Diving Springs (like Blue Spring and Alexander springs) are your closest shore dives.
For saltwater shore dives, I have headed south to either Blue Heron Bridge or Lauderdale by the Sea, which is about 2 - 2 1/2 hours. I was a bit surprised when I first started diving, and tried to find a dive boat... all the shops in the area told me that due to the reefs being so far offshore, it made more sense for a dive operation to be in Jupiter or West Palm, where the reefs are really close.
I have not found any good saltwater shore diving within an hour and a half of Cape Canaveral. I have heard mixed reviews on Fort Pierce... but if you're going to load up your kayak and drive, might as well keep heading further South.
If you do find a good dive spot close to Cape Canaveral, I would definitely be interested in knowing where it is...