I'm from south Africa and leaving the 5th of December 2016 for the UK. Don't have enough time to do my visa for France. Can I do it in the UK
From the French Government visa FAQ:
I usually live in Mali but am in Togo at present. Can I apply for a visa in Lomé? Can I send my visa application by mail to Bamako?
No. You must submit your visa application in person to the French consular office in your usual country of residence; you cannot apply by post.
You can apply for a French visa in your country of residence only.