Matt
It pretty much depends on the time of year, but Corbiere lighthouse often produces decent Bass during the summer and autumn months, as well as the gullies around La Rocque and La Hocq during the summer. also Elizabeth Castle on a low tide fished on the seaward side. A word of warning though - if you fish the gullies around La Rocque & La Hocq, then fish the tide on the way out and leave at least an hour, possibly two, before low water to start making your way back to shore, as the tide comes in incredibly fast around here.
You may want to check out for futher bass related info:-Jersey Bass
La Saie on the north coast (not far from St Catherines breakwater) often fishes well at dawn using plugs. Walk down the slip, and fish from the rocky reefs which lead from the beach. If you fancy some good garfish / mackerel action, La Saie again on the opposite side if the slip, fishes well in the spring/summer. You might also what to try Noirmont Point too!!
Regs
Paul