You would need an EU bio residence card. In other words, you will have to be a resident of an EU country and your spouse must hold an EU country passport.
In your case @P, you will always need a visa as long as you are a SA resident. The only advantage you have as a spouse of an EU member state is that the visa must be for free, you get placed at the top of the queue and the visa must be expedited. Cost of a UK visa is well over £1000 if I remember correctly.
If one day you wish to emigrate to the UK (no Brexit yet) the easiest way would be to move to Ireland for 3 months and apply for an Irish residency card. No visa is required for Ireland. Once you have the RC, you are free to travel throughout the EU as long as your EU spouse is accompanying you or you are traveling to meet her.
My wife has an appointment with a neurologist this Friday for nerve tests of the arms and legs. She seems a bit better as she no longer gets dizzy and has no need to cling onto me or the walls when walking. Perhaps the antibiotics she was given for her stomach cleared her ears out as well.