Visas are not required by British passport holders for a stay of less than six months, but you must have an onward ticket. Restricted items include flowers, fruit, vegetables, meats, plants and firearms. Do check in two hours before departure for international flights, and confirm onward tickets during the visit. No vaccinations are required unless you are coming from an area with a recent outbreak of disease such as cholera. Protect your health abroad published by DHSS if you have specific concerns.
Tap water is generally safe to drink.
Mosquitos and biting insects can be a nuisance but there is no malaria. A wide range of drugs is available at pharmacies but may be American rather than British so bring a supply of any specific requirements. Medical insurance is recommended. Climate and clothing Temperatures in Kingston and other coastal areas average between 27 and 32 degrees Centigrade during the day with the nights being about five degrees cooler. Rainy seasons are May to June and September to October, but this is only a general guide.