I was in Namibia a month ago and had a bit of a look around with an eye to kayak fishing. The main problem is that there are very few places to launch a kayak from the beach...the waves tend to break quite powerfully on the beach ('dumper' waves, not those ones that just crumble), even though they are small, which would make it really tricky. They also often break quite unpredictably over a large area, so you could get caught out. If you are in Walvis/Swakop area you might want to have a good look at the Vierkantklip area...this place is well known for cob among the skiboat anglers and I'm sure if you manage to get out there you will get quota in no time at all...just need to find a nice gully that you can exit on. You could of course launch at Swakop slipway itself, or perhaps at the jetty (which should provide some shelter against the waves), but not sure how far you would have to paddle to find fish.
I did however watch the waves while fishing from shore at Vierkantklip and noticed that they can pick up quite a bit as the tide changes...so you could find yourself struggling to make an exit, especially as Vierkant is rocky. There is a small beach where guys swim/bodyboard...which might be a possibility. I asked around a bit and though a few of the locals have considered fishing from kayaks (there are plenty of guys who kayak in Walvis Bay lagoon just for kicks) I think the main thing is that most guys catch enough fish from shore...so haven't bothered...guys in Namibia are pretty spoiled...driving up and down the beach and fishing out the back of their bakkies with a beer in hand. Missioning out there with a kayak, and then trying to exit without getting smashed into a sandbank...well, it just doesn't make much sense to them. Here in SA we're used to suffering for our fish...
Google Earth can also be a useful tool, but as far as I can see there are no natural bays Henties side.