Briony
Go for Elements first. If you've never done much work on this type of software you can get overwhelmed . Photoshop has a lot of design and graphics tools which make it a rather bloated application. I doubt if I use more than 10% of the tools and features. ( Unfortunately I need those 10%.)
Skills you learn in Element are not wasted as they can be transported to Photoshop, should you decide to go down that route.
Lightroom is a whole different program to either Photoshop or Elements. It was designed purely for Photographers, and has those tools you need to work on an image. You can't retouch, ( well only slightly) or do clever things like multiple images, but it does help you get the best out of an image.
There is always The GIMP. Now I've not used this very much as I have Photoshop, but from all reports it's a excellent program and has may Photoshop like features. Even more important it's FREE.
From what you say you want I would think Elements is just what you want. Simple and easy to use. When you find you can't do what you want in Elements then look at other programs