International trains in Europe are a good option but you need to take a full day. The best website to check all possibilities is https://www.bahn.de which exists in many languages. International buses are also a good option, see https://global.flixbus.com and finally, carpooling is recommended, see https://www.blablacar.com.
The nearest airport to Toruń is Bydgoszcz (BZG) but there are not may flights (Dublin, Stansted, Birmingham). You can either fly to Warsaw Chopin Airport (WAW) or to Berlin Brandenburg Airport (BER). Either way, you can take a train, a Flixbus, or a car.
Arriving at Warsaw, you can take the train from Warszawa Zachodnia to Toruń Główny with no changes and takes about three hours. Flixbus runs to Toruń in four to five hours. By car it is 2.5 hours to Toruń.
The train runs from Berlin Brandenburg airport to Toruń Główny with two changes and takes about six hours. Flixbus runs to Toruń in about six hours. By car it is four hours to Toruń.