We went in February and had a great time. The zoo is fun, and we went on a tour of some bunkers with Jersey War Tours. Swam in the tidal pool. Didn't have a chance to go to the underground war tunnels but would do that next time.
We had a great night out starting in JBs but I think it might be closed now, playing table tennis and making friends with the bar woman and the only other 2 people in there who turned out to be policeman. The bar woman kept giving us pickle backs, then we went to Tiki hut and played pool really badly. It was rough the next day. But we've still got a group WhatsApp going.
Go to the beaches, the waters lovely right now. Trick is to go to a beach on the opposite side the wind is blowing from.
Great bus service.