I second G-ALHI, Which Taxcalc is well worth thirty quid. I comes with full instructions, handles just about all taxation scenarios, and will print out you return or your R40 reclaim form for you (or even e-file if you're that brave
)
Last year I had income from salary (two employers), share dividends, capital gains, property income, bank interest and refunded pension contributions. There was a box for all of them, and at the end it printed out the return forms and spat out the magic 'on account' figures to be paid in January and July .
Couldn't have been easier. Certainly not worth paying a tax advisor for.