The busses do run all over the Island, but if you decide to hire a car, just hire a small one as the roads are quite narrow,many without pavements, but the drivers are very good ( max. speed limit is 40mph ) You can buy a Jersey Pass for £59 for 6 days which will take you into most attractions. Gerald Durrells wild life park, The german tunnels, Mont Orgueil castle, Elizabeth Castle, Living Legend, Samares Manor and the Jersey Museum is good too,( not Stuffy )
St. Helier shops do not open on a Sunday,it is a good idea to get the bus to St. Helier as parking is not too good there.
You will get a map of the Island and a small guide book when you arrive at the airporrt
My husband & I are going to Jersey for the sixth time at the end of August, we love the place !!