If you really decided to learn GAL and PAL (not FPGA and CPLD), the best way is to go to the official site of Lattice: https://www.latticesemi.com/
There you will find everything you need: parts, datasheets, cable schematic, 6-months trial development tools etc.
There are many compliers such as Palasm, wincupl integrated in protel can work with GAL.
Besides complier, a GAL programmer is needed, buy universal programmer and you can start immediately. If you like to built one yourself, seach on the web for circuit. There are many design.