Can i get a british passport?

You can only have a British passport if you are a British citizen. So the question is, are you a British citizen? How did your father become one? If he is one because he was born in the UK, or naturalised as a British citizen, then he is a British citizen "not by descent" and that makes you a British citizen by descent provided that he was married to your mother when you were born or legitimised you by marrying her later. Otherwise, British citizenship can only pass down one generation born outside the UK and if he himself was born outside the UK, then you don't have it. The supporting documents required to prove you are British if you apply for a British passport are listed at http://ukinsouthafrica.fco.gov.uk/en/help-for-british-nationals/passports/southafricappt/first-british-passport/ and if you can't supply everything required, you won't get one. The significance of 1 January 1983 appearing on that page is that British nationality law radically changed from that date under the British Nationality Act 1981, and that's why the documentation requirements are different.

You cannot have a British passport, if you are not a British citizen. First, you need to become a British citizen, then you can get a British passport. If your father became a British citizen by naturalisation before your birth, then you are elegible to become a British citizen by descent, since naturalised British citizens can pass their citizenship to children born abroad. If your father became a British by descent (because of his mother or father were British-born), under the new law, your father can register you as a British citizen by registration, only if you are under 18 years old. If your father gave up his British citizenship before your birth, then you are not elegible to become British For more information, please contact the British High Commission in South Africa.

http://www.bia.homeoffice.gov.uk/ here is the website that issues British passports. Have a good read. I am sure you can't but have a look.