PS is one of those programs that, if you understand what it is you're trying to achieve, is quite easy. It's often the vast scale of what's on offer with this software that daunts people but if it's say image tweaking and cloning then it's very easy to get used to.
As Ady N suggests, tutorial books are a great starting point. There are a few PS magazines out and I'm sure I've seen bookazines produced by the same publishers that are effectively the best bits of the magazines condensed into one book. I'd look online or in WH Smiths for these.
Also, there are some brilliant online tutorial websites that offer great, step-by-step advice on how to do many tasks. Hey, there are even tutorials on this website that could help you out.
I wouldn't suggest going out and buying the latest copy - it's an expensive mistake if you don't get on with it. Either buy PS Elements, a slimmed-down version designed for the everyday Joe, or get hold of a used version of CS or CS2 (from a few years ago) that will give you massive power to progress for relatively little outlay. I've actually been thinking about selling mine but looking at the prices - £100 for a full Photoshop/Illustrator/InDesign/Bridge package I might as well keep it. Like most software, old versions don't seem to hold their price very well so there are bargains to be had. Fleabay is the obvious place to look for used versions.
Also, look on the Adobe website; there are loads of downloads that give you 30-day trial access and there are loads of resource features on there that will give you a helping hand.
What is it you're most wanting to do? That answer could help slim down the options.
If you want a photographers tool (as opposed to the graphic/illustration features within PS) why not look at Lightroom? I've used PS since 1995 and over the last year or two I've realised that 99.9% of the things i want to do can be done in Lightroom. It's very good at image management (getting all your images together, sorting them, keywording etc) plus it has some seriously powerful adjustment functions that are easily accessible on one screen, as opposed to the drop-down menus of PS. It's about £180 new but you can get older copies - someone has an old version for sale in the classified for £50. Download the trial to see if it suits.
You can see there are options out there, and that's without even mentioning any of the others, which i'm sure someone more qualified to do so will talk about.
Courses are good but there's nothing like learning at your own pace. It's easy to do so, providing you don't mind spending time on the task and looking in the right place for information that will help you to understand how you can achieve what you want
