It is many years since I was on holiday with my family in Jersey and I was far too young to have any taken any photographs to aid my memory. (However I do recollect borrowing my sister's camera and firing off 12 shots of a distant hotel which included my finger poking in from the side).
Having undertaken quite a lot of research I decided that the most fruitful areas for sunset photography would be La Corbiére Lighthouse in the southwest corner and Plémont beach in the northwest. Fortunately Jersey is extremely small so one can drive from one end to the other in 30 minutes and evening photography can easily be fitted around the evening meal in the hotel.
I visited La Corbiére twice; once for the sunset and the second time to do some long exposure photography of the water on the causeway. I always thought Saltwick Bay was difficult to predict but the Jersey tides are extreme and fast moving so I learnt to allow 3 hours either side of low tide to see the water lapping the causeway. As the causeway has dips and troughs you have to work quickly before at least one section of the causeway is submerged or well clear of the sea.
Plémont beach is absolutely wonderful but the three hour rule works here as well especially as there is no beach at all at high tide. The tide rises so fast that people are often cut off from safety because there are high rocky outcrops which prevent a safe escape from the beach. Coastguards patrol during the day but not in the evening so take care. I arrived actually at low tide so I knew that I'd be fine for a couple of hours.