I used the most recent update of my Citroen SatNav.
Whatever you are using, just head into Rouen town centre. Landmarks to watch out for are the old chateau ruins on the left as you approach the city, then a few miles later ‘Le Buffalo Grill’ roundabout with its associated cows. You will then be fed onto a series of industrial estate dual carriageways, with associated cut and thrust driving. Stick at it, heading downsteam beside the (out of sight) river to your right and the railways to your left. You are aiming to cross the river. Once over Seine and up into the tunnels you are sorted.
If you happen to be passing Tours en route, say hello to Doreen, the World’s Best Mother in Law!