Should I take a tinnie to Ningaloo?

you will regret not taking it when you get there . Great fishing, diving etc just off shore with one. We have always taken one and launched of the beach in good weather.
Have fun, envious, great place been there heaps of time. Maybe a bit more crowded now.

Depends where your coming from , carted our 3.6 tinnie on the roof from the east coast to the west coast and in a 23,000klm 6mth round trip only put the boat in the water 2x , smallish boat + large fast tides do not make for safe boating , Each to their own.

You'll have no trouble in the extensive lagoon areas behind the reef launching from Tantabiddi. Some superb snorkelling nearby and should be good spots for spangled emporer etc. Also squid over weed bank areas.

If you're lucky and get best weather you could even get out the back as it's not far out from the ramps.

Cheers.

3.3m is not too small, provided only 2-3passengers maximum with 9-15hp outboard. Definitely take usual safety gear [flares, lifejacket, oars, anchor]. Superb fishing after sunset inside the reef [squid, snapper & sharks over sand!]. Spectacular snorkelling along inside fringe of reef, best on slack tide with low/no wind. Some launch spots [e.g. Osprey Bay, Pilgramunna, Neds Camp and Tulki] are within proximity to passages in the reef enabling access to open ocean and some occasional good bottom fishing or trawling [best with light winds, slack tide, near to sunset/sunrise]. You could regret not having a dinghy at Ningaloo [provided you're staying for more than just a few days]. Enjoy ;-)