Its a great dive lots to see, but you want to be there and ready to go about 1 hr or so before high tide, not a place to go solo..
not a place to go with somebody you don't trust 100% either;
i usually go solo, but i'm just a guy who went in there in 3+ ft waves.
it's all about knowing the site, the way the current push against the shore depending on the tide, the topography in general and to be able to find your way back to the entrance / exit site without surfacing. there is some magnetic variation on the site as well so it's not a place to go alone unless it's dead calm and you have some cold water experience, the stamina to bring your stuff down the slope and up after and not the last a little bit of adventure spirit.
visibility depends on the tide, HIGHLY. on the right from the entrance point (the "sewer outlet" is a boulder field, full of vegetation and life, on the left is a stony plateau, not so much life but much easier to observe. you can find stripers and blues in the inlet of the "sewer", other fish are usually a little more away. lobsters everywhere, quite a lot of keepers (why are the commercial guys complaining i have no clue, well, their traps are about as dense in there as the sardines in a can, i guess that's why, but the lobsters have no interest in them, plenty on other stuff to eat and places to hide). i recommend descending to the bottom right in the "sewer outlet" and following the wall on your right side and than continue further to about 30-40 ft, than go to right. on your way back you will bump into the stone plateau, at that point you turn around for like 50ft and head back to the shore. you will bump into the wall again and it will take back to the inlet. keep regulator in your mouth , fins on and don't be ashamed / afraid to crawl on your way back - if the waves are significant it's the only way to get out. if not sure you can make it straight into the inlet surface from where the bottom is about 30ft and get an accurate bearing on it. any mistake on a not very calm day might put you in hospital, or worse, ...
good luck.
p.s. some shops in the area arrange for shore dives at cathedral but it's quite rare, now you know why, ...
p.p.s. i know my advice is late but maybe it will benefit somebody else. I can make a sketch of the site as well.
p.p.p.s. if this is the "legendary" rebreather Dave Sutton, any chance you guys are running to the 853 this weekend? i was hoping to visit it this year.