There are many routes and methods the intrepid traveller may use to arrive in Utila.

The most straightforward method is to fly to Roatan (Juan Manuel Galvez International Airport RTB) via Houston and then get a ferry or small plane to the island. An alternative route is to fly to San Pedro Sula (via Madrid if you are starting from the UK). Then there is a three-hour plus taxi ride to La Ceiba and the ferry to Utila. The latter is a longer route and if you are going to cross Honduras a reasonable level of Spanish would be sensible.

In addition you need to check with the Honduran authorities as to whether or not you need a visa and how long you can stay in the county as a tourist.