I did my first North Sea crossing - Harwich to Ostend at the end of May (in a 31footer). You should work out your journey time and arrive (with a good margin) in daylight. 75nm at say 4knots = 20 hours ish. Crossing the big TSS is probably as easy at night as in day.
Don't take surplus red diesel in cans unless you put it in your tank the moment you arrive. It is illegal in cans. Passports, VHF licence and insurance plus any other boat papers essential as the police did board some boats.