Never been there so don't know what's good there. Birds, insects, flowers, landscape, I interested in them all. Portraits too but I assume that won't be the prime reason for going to Chek Jawa.
Will you be at beach/water level or on the boardwalk?
Boardwalk, standing height is about 10-15ft to the seabed. Bring suitable zoom to be able to work from 30-50 ft. The longer, the more area you can cover but tripod is something to consider with longer lens. Macros will be quite useless here.
At beach/water level, macro, primes, short zooms will be useful. If you trip, everything goes for a dunking. You be stepping on stones, weeds, mud and all sorts of stuff on the seabed, don't be too sure you won't trip. Not sure if you're allow to do this anymore.
Insects - there are no insects out at sea save for those blown out - bad choice of place to find them.
Birds, another animal and lens adventure. There are large brown kites(?). If you're lucky you can catch one swooping in to pick off a fish, seen that quite a few times. But you won't see them near at low tides.
Polarised filters will come in handy for water reflections.
Go on days with 0.2 or lower tides, else you'll only see water. Likely times when this occurs are sunrise and sunset times 5-7 o'clock.
Bring sunblock, hat and have fun.