Decent areas are West London (Kensington and Chelsea, bits of Notting Hill, etc, bits of Fulham, Primrose Hill).

Affordable? Well, you can't possibly know that before you know how much you will earn. As you can imagine affordability and desirability are mutually exclusive.

Also do not expect to buy a property hers any time soon, unless you are filthy rich, you will not get a mortgage because you don't have a credit history in the UK, so most likely you'll end renting, if you are not a high earner you will have to share a flat with strangers or rent a single room (which are not big in London). Welcome to lovely UK.

You should check the conditions of your visa, that will pretty much tell you what you can do in regards to jobs, if you have got some savings maybe you should take a couple of weeks to check things around in London and then apply for jobs.

if you are not sitting ina pot of money then it is quite temerary to come just like that, and may end like many South Africans: as pub bar tenders :-)