Arriving from Uganda, a yellow fever certificate is required: WHO lists Uganda as a transmission risk.
Driving on a Uganda license
Cuba and Uganda are both party to the 1949 Geneva Convention & 1968 Vienna Convention, so an International Driving Permit issued in Uganda is one Cuba is bound to recognize.
Whether a permit is required alongside your national license is set by national road law, which we have not checked for this pair.
Passport validity — The UK Foreign Office says your passport must have an expiry date at least 6 months after the date you arrive in Cuba and 3 months after your planned departure date.
D'Viajeros traveler information form — Cuba's D'Viajeros site says it is mandatory for each passenger to complete the advance traveller information, truthfully, for the Immigration and Foreigners Directorate, the General Customs of the Republic and the Ministry of Public Health. The UK government says to complete it within 72 hours before entering Cuba, that you'll get a QR code by email to show on arrival, electronically or printed, and that airlines check completion of the form at check-in.
No official source states a rule on: proof of funds.
Convention on Road Traffic, Geneva, 19 September 1949 (UNTS vol. 125, p. 3); Convention on Road Traffic, Vienna, 8 November 1968 (UNTS vol. 1042, p. 17)
International Health Regulations (2005), Article 36 and Annex 7; WHO International Travel and Health, Annex 1, 18 November 2022 (revised 3 January 2023)