I used Trevor Thom books for my PPL and CPL theory and found them to be almost spot on. The only difference is that I didnt use it for my Echo loading in the CPL part as I took a class for that bit.
For practice exmas I found that he was fairly close to the real thing and although with the new Cyber system I'm not sure anymore. For practice exams (CPL) try the ones from Val Dyse and Holland (not sure about the spelling). They are VERY VERY hard questions, much harder than the TT books but are good for the practice. Was failing the VD&H questions, doing really well with the TT questions and ended up passing the CPL first go.\
Hope that helps.
Twin