Thank you so much for your and most helpful reply, Alice.
The only thing that prevents me from self publishing is that the big publishing houses, with whom I still have a chance as they have had my submission for three weeks now, make it very clear that they won't
touch a book that has already been self published. This reduces my chances of getting any follow up books in my trilogy published either – or does it? I am in such a quandary as what to do. But I know that the one thing I won't be doing is paying nearly £3000 for what sounds like a shoddy product.
I could write to the big publishing houses in South Africa, telling them that there is interest in my book here in the UK, and asking them roughly how much longer I need to wait before they come back to me. But I'm terrified that they might think that if I have the possibility of a contract here, then I should go through with it.
But on the other hand, they might think that since I too have interest in my book here in the UK, that means that there is a good chance that they too will be able to sell it here in this country. But I really need is a crystal ball

Failing that, all the help and advice I can get from fellow writers or wannabe writers on this forum.
Thanks again for your advice.