Get your chest x-rays and medical in SA as it's much cheaper! I'ts also quicker!I went to SA last year with a 3 month old baby and NO injections were needed. I specifically checked with our GP as we were travelling with such a young baby. All depends were you are going to be. We stayed in Cape Town and it is a major world city as far as healthcare is concerned. We too are thinking of emigrating later this year to SA and for the visa you will need a chest xray unless going on a tourist visa.
We rocked up to a medical centre in 1 1/2 hrs the whole family had full medicals and xrays!
We came in on tourist visa's and applied within SA. Depending which Visa your getting.