I have the full set of Trevor Thom books and despite being rather "dry" found them an excellent study aid for my PPL course which I passed last year. I also passed each exam first time with the help of the PPL Confuser (make sure you get the LATEST edition if you intend buying it).
May be worth seeing if you can convince your folks to buy the complete study pack from Flightstore (ie all the Thom books and the confuser plus other useful bits and pieces).
Best of luck with your future flying training!
Adam