You should be able to get out shore diving from Coconut Bay, Turtle Reef ( Macabuca ) and Lighthouse. They are usually sheltered.
If the wind is blowing from the North or NE, Cobalt will be a blown out.
I would not bother with Sunset, Smith's or Eden Rock unless it is impossible to dive up in the Northwest.
If most other places are not diveable, I'd check with Sunset House as a last resort in that it is possible to get out to the reef from their salt water pool, even if the steps have been pulled out. If there is no shore diving, it is always possible to go boat diving as there is always a leeward shore.
Last January, we got out boat diving every day for a week and shore diving 4 days out of 7.
Diversteve, you are correct. Cobalt and Lighthouse diving are both run by Divetech and they will transport.
Divetech boat packages usually include unlimited shore diving at Lighthouse, Cobalt.
If the seas are calm, the miniwall at Cobalt is a fabulous shore dive. Long swim out but worth it.