You must obtain a volunteer visa for travel to Ghana. You must apply for your visa before you leave, as no visas are issued in the airport on arrival.
Your entry to Ghana may be refused if there is only six months left on your passport before it expires on the date you plan to enter Ghana. So the first thing to do is check your passport and get it it renewed if there is less than six months left before it expires.
Should I choose single entry or multiple entry visa? It is really up to you. If you think you will travel outside of Ghana during your trip, you will require a multiple entry visa to enter Ghana again.
A Single Entry Visa is normally only valid for 3 months from the date of issue, this means you have to enter Ghana within those three months, so do not apply too far in advance. The advice from the Ghanaian Embassy is to submit your application for a visa one month prior to the intended date of departure.
Even though your entry visa may be valid for up to 3 months, it will automatically be valid for only 2 months upon arrival at the airport. But don't worry, you can extend your visa every 2 months for as long as you like for a cost of about $5 US per month. The school will help you with your visa extension, which can be obtained at the Department of Immigration (Monday - Friday: 8:30am - 3:00pm) in Kumasi, Accra, Sunyani, Cape Coast, Koforidua or Tamale.
Under the section Purpose of Journey, tick the box "Voluntary Work". If the visa application form you download does not have volunteering as an option under the Purpose of Journey section then you should select holiday/tourism and make a note where possible that you are volunteering.
When you have formally applied to the school you will get a letter of invitation from the school which will form part of your visa application.
You will also need either two or four passport size photographs (UK requires two and US requires four).
It is a requirement of the visa form that an applicant should possess a return air ticket.
Yellow Fever Vaccination Certificate: you must show this certificate when you arrive in Ghana. The yellow fever immunisation takes effect 10 days after the injection and lasts for 10 years. Your local GP or health clinic will be able to tell you where the nearest yellow fever clinic is located in your area.