DigiKam Is probably quite a bit like PSE, offering keywording and some management tools as well as good (though destructive) image processing tools. It didn't used to have cloning tools for dust spot removal etc, though they may have been added since I last used it. I liked their colour balance and sharpening tools better than those in Lightroom, but overall I feel Lightroom capable of creating more pleasing images (and it's non-destructive).
Darktable is a good non-destructive editor, but when I tried it, seemed less capable than LR. Raw Therapee is similar.
There's a lot of free software available if that appeals. I found I had better results with paid software, but your experience might be different, and there's a lot of satisfaction from using stuff that doesn't cost money (although you could donate).
A quick comment on Linux - I've been using it since the early 2000s and still have a box here running a couple of different DEs on Mint. For DigiKam under linux you'll need either the KDE desktop or to have most of KDE installed (your package manager should install it for you). Generally the mainstream versions work out of the box in a way to make Windows users jealous, being very very backwards compatible with hardware, but it can be a challenge to get used to if you're not comfortable with computers.
I called them direct and had the ram upgraded to 16gb for an extra £12.00...Should be here next by next Tuesday...As always, I appreciate everyone
it makes for an excellent little man cave though, no natural light, shut the door and you're isolated 
It's also the only room i've ever been allowed my Star Wars posters up in......
