Driving to the Cherbourg FerryPort, when you enter Cherbourg on the N13 (the main coastal route from Bayeux; also from St. Malo northward via Avranches and St. Lo), there's a large highway sign indicating two different routes to the port. This occurs at about Le Rocher and La Maison Bertrand. Unless you're driving a truck or other large vehicle, don't take the one with the picture of a truck (the N13 to D901). That's the longer, less direct route that is engineered to avoid steep inclines and sharp curves. If you're driving a regular car, you'll want the more direct route (the N2013 to D900).
Either route will get you there and there are plenty of signs so you won't get lost, but the truck route will take longer. Just thought I would share this as people driving to the ferry are usually on a tight schedule. See https://www.bonjourlafrance.com/travel/france/normandy/cherbourg/ferry-ports/cherbourg-ferry-port/