I live in Cape Town and hold a Life Partner visa. I am marrying my fiancé later this month who is South African. I am British. I work for New World Immigration and thought I would share my experience along with the documents and steps needed to get married here as a foreigner. We did a blog on this a year or so ago, but this is up to date info.
We decided to use the services of a marriage services officer here in Cape Town who is doing a romantic, but simple paper- based ceremony for us. He gave us the list of documents we need. This company offers all types of ceremonies. They provided a letter that we took to Home Affairs to tell them that they would officiate our wedding. 
Obviously you need your passport with a valid visa inside whether a temporary residency visa or valid stamp if you came into the country as a visitor. The following documents are necessary:
• SA ID Document certified
• Foreign Passport certified
• Custom Entry Stamp/Visa
• 3x passport size photos of couple
• Divorce Decree- clear copy with stamp (if applicable)
• Death Certificate- (if applicable)
• Marital Status Affidavit (UK Nationals I will explain below)
• Letter of Non Impediment
• 2x Witness ID/Passport
• Custom Entry Stamp/Visa of witness
• Home Affairs Approval Letter after Interview
• B131 Form –Our marriage service provides this
British Nationals will not be able to provide a letter of non impediment simply as the British High Commission does not issue them. What you need to do is to go to your nearest British Embassy and ask at the front desk for the letter stating they don’t offer a certificate of non impediment. It must be stamped by the person at the desk. It does not require an appointment.
It states:
“To whom it may concern at the South African Department of Home Affairs
Thank you for your enquiry relating to your proposed marriage in South Africa and
whether we can provide a Certificate of No Impediment.
Consular Officers in Commonwealth countries have no general powers, under the
Commissioners for Oaths Act 1889, to issue Certificates of No Impediment, certify
Documents, take oaths, affidavits, etc., which will be effectual in the United Kingdom.
As South Africa is a member of the Commonwealth, the British High Commission in
Pretoria is not in a position to issue such certificates.
The Department of Home Affairs have confirmed to us that you should instead
show your British passport and provide a copy of this letter and a sworn
affidavit stating that you are not married, and that there is no legal impediment
to your intended marriage. “
So simply collect the letter and then go to your nearest SA police station and ask for an affidavit form in which you can write down that you are not married and have no legal impediment to your intended marriage. Both of you sign it.
One you have this, you must go to a Home Affairs office near you. You will take your affidavit or letter of non impediment, passports, divorce decree if applicable, and we took the letter from our marriage officer. They took our documents to verify and said they would then phone us with an appointment date once they verified our information. We were a bit worried as to how long it was going to take as Home Affairs would not give us a timeline. Luckily, they called us back and we had our interview the following week. I found the immigration department at the Bellville office to be very helpful.
The Interview:
My fiancé and I were interviewed separately. You are warned to answer the questions truthfully and be as open as possible. I was asked the following questions. When did I first meet my fiancé and where. What did we discuss? When was that? When was he divorced? When did he propose? What type of wedding are we planning to have and when? Do we want children? His parent’s names and his sibling names. Are they alive, married, and their occupations. Where do they live? Do we have children and their names and birthday? Where do we stay now? Do we own the house? Do we intend to stay in South Africa? Basically the interview lasted a half hour. When you answer a question, the interviewer takes notes and compares your answers to the next person being interviewed. I think they make up questions as they go along based on what you say.
Once you finish the interview, the Home Affairs representative will write a letter stating whether they feel your intent to marry is genuine. You need this letter to register your marriage.
Good luck.
If you need assistance with renewing your current Life Partner Visa, or to get a Spousal Visa please contact me on 021 555 0951 or contact sarah@nwisouthafrica.co.za