Passport

You must be in possession of a valid passport, and it must remain valid beyond your expected date of departure from Uganda. If on a gap year it may be wise to renew your passport if it's due to expire immediately after your intended stay, otherwise any plans to stay a little longer will be thwarted.

Always carry a photocopy or two of your passport in case your original becomes lost. You can't travel on the photocopy but it will help to prove that you are entitled to a passport, and will show that you had a valid entry visa stamped in the passport when you arrived in Uganda. Obviously, don't keep the photocopies in the same place as the original.

Entry Visa

All UK citizens will require an entry visa, as do citizens of the USA and most European countries. For current visa requirements, including visa fees, check the web page the Ugandan Ministry of Foreign Affairs where a list of exempt countries is maintained. At the time of writing, a Single Entry Visa will cost you 30 US dollars, and a Multiple Entry 6 month visa will set you back 80 US dollars.

You can apply for a visa via your country's Ugandan embassy before leaving, or purchase one upon arrival in Uganda. There is no great advantage to purchasing the visa before you travel as the process is quick and easy, and you will have to join the queue to go through immigration anyway. Contrary to some sources, passport size photographs are not needed when applying for a visa in Uganda, but it's advisable to take a few anyway as they may come in useful, even if you just give them away to new friends.

Check carefully if anyone offers to extend your visa whilst in Uganda. Even authorised gap year agencies have been known to unwittingly get visa extensions that were not gained through the right channels. This can lead to your visa being invalid, your passport being put on a black list and you being asked/told to leave the country.