Pepper spray is a great self defense tool. The gelling stuff I am skeptical of after seeing this video:

Funny I basically paraphrased his opening lines before finding that video again.

I don't know about its availability in SA but in the US I have tried carrying several brands in different sizes and I've settled for now on POM. Which that YouTube channel turned me on to in the first place. But for carrying in men's pants, like in the watch pocket, it's super compact but safe against accidental discharge and effective for a spray of probably 10 seconds at ~5 meters.

For a woman, with the possibility of purse carry, a bigger one is probably a better idea. Not sure what brands are available to you there but Mace in the US is a pretty respected brand. Sabre is well known too, but they commonly have a twisting safety mechanism which is bad in general but a terrible idea if it were loose in your purse.

Whatever you end up getting, see if you can get a practice one or a practice cartridge that can be installed in the housing. Should be pretty cheap, and a huge value. Understanding the expected spray behavior and getting draw and fire practice with it could make the difference between a bad day and a really bad day.