I dont know Port Denison but have sailed a lot at Horrocks and think it is a top spot. As mentioned there is a stronh north bound current in front of the jetty and boat ramp, but if you walk up the beach to the first little headland a 100m north of the boat ramp the current dissispates and is suitable for a less experienced sailor.
Straight out from there is ' the gap' where boats escape the lagoon. the waves are excellent here. Larger than most other spots on the coast and well suited to windsurfing. Great fun.
If you are going to Horrocks for Easter you might have trouble finding somewhere to stay as it gets booked out quite early. Even the campsite.
Little Bay is also very nice, but a bit feral camping with uncontrolled camping creating quite a mess in my view.
Hope this helps
Cheers
Dave