I've plumped for the earlier ferry about 17:00ish this year and gets me to Dieppe around 23:00ish. In 2015, I found I got no sleep on the ferry thanks to people talking, laughing and wandering about all night that I arrived in France shattered after being up all day and driving down to Newhaven, up all night and then drove down to Vernon somehow. At one point, some bloke stood up and told a big gang of girls and women to shut up which was quiet amusing but it just made them start laughing and tittering for ages. This year, I can stay awake on the crossing, get to Dieppe, park up somewhere quiet, few hours sleep and then a leisurely drive to the hotel from just after dawn.