Hi, thanks for adding lots of detail around Windermere recently. 

I'd say that the lower part of Thwaites Lane is best tagged as residential based on the wiki and local knowledge - there's houses facing it and addressed off it, and it's part of the public highway network. width/lanes/sidewalk tags could be added to indicate its characteristics. 

Feel free to drop me a message if there's anything local you want to discuss! :)