Completely newbie so basic question - when I make adjustments to a photo in Lightroom Mobile and save the changes, does this mean that I have lost the original image? If not, how do I see the original image if I want to without deleting the newly changed one and if I should ever remove Lightroom Mobile then do the changes images stay? Thanks for your help.
In Lightroom is not possible to "save" changes to images. Changes are incrementally saved in a catalog. In Lightroom Mobile or for the cloud that catalog is not readily accessible to the user. In order for you to have an actual file containing the changes that you have made using Lightroom it is necessary for you to export a copy because the master image is not modified. The master image remains in its pristine state. In the desktop version of Lightroom you can always see that original image by pressing the "\" key to alternate between the edited stage and the original. I don't use Lightroom mobile on the iPhone enough to know how it would be done on that device.
I don't use LR mobile on my iPad or iPhone because it takes a lot of space. However, based on another response before mine, your master image on desktop is not changed. On the old LR, aka LR classic I guess, you can go to your history and see all the changes you made. Once again, your original unaltered image is not damaged.
Also, when you say in LR Mobile, do you have the new LR or a different kind of LR because i have 2 different LR on my new iPad... One that has the automatic cloud storage, and the other one does not