In reply to Stone_donkey:
I'm using quite an old version of Lightroom. My catalogue etc is located in
MyPictures, Lightroom, then sub folders are: Backups; Lightroom 3 Catalogue Reviews; and Lightroom Settings.
I'd keep the last two Backups and delete the others, then make a copy of the Lightroom folder and it's sub folders.
Is it really necessary to do a wipe before you reinstall Windows 10 ? I think you should be able to reinstall without wiping your data.