The weather should be excellent, (compared to the UK) warm, dry and sunny. There is no danger of hurricanes in January. Cuba is infamous for mosquitoes, but on many visits I have never encountered them, in Havana and Holguin. I have not been to Varadero. The Cuban Convertible Peso, (CUC) is worth a little more than a US dollar. It can only be bought in Cuba, in exchange for £ or Euros, and can be obtained from the ATMs. The Cuban Peso (CUP) , used by Cubans, is worth a few pence only, and will not buy you much. I hope that you have an excellent holiday! Adios.