erasmusdt - do you really not understand this?

This is just NOT going to work unless you either get a visa in your own right, or wait until you can enter the UK with your wife (and you will need to check if you can legally be the breadwinner if she is the one with the ancestral visa as the UK government web site suggests that this may NOT be the case).

If you enter the UK illegally, or on a tourist visa, you will NOT be able to work here.

And no one here on Flyertalk is going to help you break the law. It would be stupid and immoral of us to do so.

Also... while it's perhaps none of my business...: Your wife is going through a difficult pregnancy. You have other children. Shouldn't your place be with your family in South Africa?