Are you alllowed to take the theoretical ppl test outside the country where you did your training for the licence ? Make sure that is possible. In any case you will need to get from your school where you did your training a written confirmation of PPL course enrollement or completion.
Slovenia is a very easy going country and everybody speaks very good english there in the aviation community, Bureaucratically it is preferable to ENAC Italy, as it is very straightforward and you can do almost everything by mail or online real quick, you don't need to go there in person for licence or rating endorsements once you have taken the tests.
The easiest an quickest way would be to inquire googling for ppl training facilities in Portoroz Slovenia around the corner from Trieste Italy. Good luck !