Good on you for trying to help a snake
Im familiar with the area you are in, presuming its Gansbaai as my in laws are in Elim, which is not too far. I know Armata (he is on this site) facilitates a snake and awareness course that is great, and helps in identifying the various species as well, i know he does courses in Stanford very now and then, maybe you can PM him and get him to mail you should he have a course next.
If you could give me a brief description of the snake, Im sure I can give you an idea what you looking at. The snakes you generally have to worry about in your area would be puff Adder, boomslang, and the Cape cobra, there are maybe Rinkhals as well. the Puff Adder is a short stocky snake with yellow Chevron markings and a Shovel shaped head, the smaller Adder species in a nutshell will be smaller and not as brightly coloured but also not to be messed with.
The boomslang will be a slender fast moving green or brownish snake with "bulging eyes"
And the cobra and Rinkhals wil generally hood when confronted, the Rinkhals can however "spit" venom.
I agree the Johann Marais book is great, however if you prefer not to spend that cash, get a smallish book published by Struik, and cost about R50, but does the job as well!
If you need any details, please do not hesitate to pm me, and I can try and fill the gaps.