According to the official T&T site at www.gotrinidadandtobago.com/travel-information/
a visa IS required for visitors from Poland. As you will see, these notes say "Applications for entry visas must be submitted to a Trinidad and Tobago Mission abroad or where there is no office, to a British Embassy or Consulate in a non-Commonwealth country." I doubt that they have an embassy in Poland, so perhaps your friend can apply in London. Unfortunately, the link to the T&T Immigration Dvision is broken and I've been unable to find a link for further information. Scout through that site and perhaps contact them via the relevant page there.