If I can put my 2 cents in ..... I started with PSE6 and am still working in it! While I'm sure there is a lot I'm missing - what I don't have, I don't miss and I never have any trouble creating layouts.
The only thing is that nowadays many styles and actions do not work in PSE versions below 10, I think.
I'd say if you want to dive in with what you have - go ahead! You can always upgrade and your learning will never be lost.