Hey mate,
I'm in SA too. I do think though that 100L will be a bit small and slippery to get the basics well. 100L was my first board once i could plane in the harness and then gradually moved back to footstraps on that (but i was only about 60kg at the time, maybe even a little less). I would defently be looking for something a little bigger, like the two GO's 133 and 144 for sale in SA at the moment. But obviouisily that a lot of money to forke out so just keep your eye open and something like that will come up. But thats the sort of thing you need i reckon. Would be perfect and you would progress very quickly.
Anyway catch you out on the water some time hopefully, were the white ute PACKED with gear and me and my old man sail together (i cant drive yet either

).
Cheers
Bubs