Getting to Gliwice is pretty straightforward as the city is easily accessed by frequently running trains from Katowice's main station although be aware that the main train station is under construction until further notice. Lying another 10 to 15 minutes beyond Zabrze, the journey takes about 25-35 minutes depending on your choice of train and should cost you between 8 and 20zł. Ticket windows in the station are open 04:45 - 21:10 and they accept credit cards. The bus station is in quite close and a bit more grisly consisting of one small shabby room. Don't bother waiting in line at the ticket windows because you can buy all tickets from the drivers. Just northeast of the centre at ul. Bohaterów Getta Warszawskiego 12, a 7 minute walk down ul. Zwycięstwa will send you straight into Gliwice's Rynek.
If travelling by car, getting to Gliwice is a snip. Only 27km west of Katowice, Gliwice is just off the A4 freeway, the stretch between Katowice and Gliwice of which is free. So whichever direction you are coming from, hop on the A4 and get off at the Gliwice exit following the signs to the 'Centrum.' Boom.