I self-studied all my theory with Bob Tait's books and they were right on the mark. I used them from GFPT through to CPL and IREX and found them to be extremely helpful in uncluttering complex theory and preparing for the written exams.
Further on in your training, you will also find his material useful for instrument renewals and flight instruction briefing notes (as I have).
BTW, I don't know Bob Tait and get no credit for the contents of this post.