How tricky is business economics?Watch
I'd consider a lot of it to be straightforward. The typical books I would recommend looking into to get an idea for economics at uni level are:
Basic Econometrics by Gujurati
Principles of Macroeconomics by Mankiw
A lot of it will be based on discussing theories and see how they clash. You will need to understand the models. memorise some derivations, be able to calculate basic maths, and differentiate some equations, but not that much more than that unless you want to opt for the harder stuff. I found economics at degree level fun, and a lot less stressful than A Levels.