A route going around the UK through the mid Atlantic Gap and hooking down through the Greenland Iceland Gap to occupied Europe via the North Sea would actually be safer for German convoys. Though far less direct they would be passing through areas beyond the range of early submarines and in many cases in areas of poor sortie efficiency by early-mid naval bombers.
In the close in zones such as the North Sea the convoys would enjoy comparatively ample protection from friendly fighters against naval bombers and the poor weather of the North Sea makes them far more difficult to spot and engage, both by naval bombers and by enemy convoy raiders. These areas are also easier to maintain outright air superiority in as Germany as they do not geographically coincide with the imperative of maintaining dominance over the channel, any contestation of the North Sea zones by the UK risks weakening the channel air barrier and thus puts England at the risk of a combined Sea air landing while it costs Germany comparatively little to assert reasonable superiority over these zones.
