As you can see the beach has amazing views right out to Sydney Heads, some good snorkeling, a sheltered swimming pool, and grass to lounge about on and munch your picnic goodies. There is some shade provided by a few trees, especially later on in the day when the sun is in the west.
Getting to Fairlight Beach could not be easier. Simply catch the ferry to Manly Wharf, turn left when you hit the shore, and keep going until you get there. It should take you no longer than 15 minutes, 5 if you can walk faster than my grandma.
Here is a map in case you somehow manage to get lost.
Once you've had your snorkel, swim, and picnic you could also check out the Manly Markets. Or if you did not pack a picnic, head back into Manly for your lunch or dinner before hopping on the ferry to make your way back home.