I am expecting 1million pounds to come from Spain from an uncle that died.
What will the taxation be on this money coming to me in South Africa?

It appears that the estate duty is not payable if your uncle was not a South African resident.
If the deceased was ordinarily resident in SA, his/her foreign property is also subject to estate duty.http://www.sars.gov.za/Tools/Documents/DocumentDownload.asp?FileID=55034
One would expect that if there is a Spanish estate tax, the estate will be responsible for that.

To be sure, you should consult a SA tax professional.