Katrin Eismann books on Photoshop are ok but a bit dated, you can probably find them online. The problem with Adobe CC is by the time a book is written it's already out of date, so the best resources in my opinion are probably YouTube videos. Lynda.com/LinkedIn has a few bits, so does skillshare, probably good for a beginne but lacking in advanced skills. There's loads on Udemy but it's mostly absolute garbage so be careful, even if the course is on some sort of 90% sale it might not be worth it.
My advice would be to do a basic intro course, and then start editing, everytime you get stuck google the solution or watch a video on that topic.
One watchout with YouTube is the styles are all very samey and they will push you towards a certain look.
Personally I wouldn't bother. A lot of high street stores and supermarkets offer photo printing for a few pence per image and the quality is massively superior to those products.