The government of President Raúl Castro stated that as of May 1 foreigners and Cubans living in other countries may enter Cuba only if they carry a travel insurance policy with medical coverage.
Policies must be issued by insurers recognized in Cuba, and this is a short list.
Effectively, you will have to buy travel insurance from a state insurer at the point of entry. There will be sales points at every point of entry into Cuba, and if you refuse to buy cover you will be sent home.
As once out of Cuba, you will find it very difficult to claim on a Cuban insurance, you should also buy normal travel insurance before leaving the UK.
Effectively, the travel insurance rule is an entry tax.
According to official figures, 2.4 million people, of whom nearly 300 thousand Cubans living abroad, visited Cuba in 2009.