Aircrafts withdraw from battle remaining in the territories where the battle is fought, in this case Norway.
In the non combat move they have to land in the same way you do if you had won the battle. So they may come back to England, land on AC or in any other legal space they can reach.
You guys are the best! Next game will be alot better as we will actually know what we’re doing with air units, especially with Japan and the US, as battles around the Pacific were the main confusion point, thanks switch and paintbrush…
Cheers