I have now found an on-line source that has the full set of Phillimore marriage indexes for Nottinghamshire. I suspect the links may change in future, but at the time of writing:
The LDS Family Search home page has at the bottom a link to labs, which leads to
https://labs.familysearch.org/. That in turn has a link to the Books beta site. Then search for Nottinghamshire marriages.
The files are fairly large and can be slow to load.
The attached file gives dates and the volume and page number for those parishes that have been indexed.
