Personal experience is that CBT is a waste of time and money as far as absorbing information is concerned. I much prefer reading a book. Again, personal experience (using the Thom series) is that there is within them all that you need for the examinations, there are even trial questions at the end of each volume, if you wish to indulge in that sort of thing.
As far as simulators upon a computer are concerned, I looked as the MS type and found it irritatingly fussy and mostly irrelevant in relation to PPL - I did not, therefore, use any during the course, nor have I since. RANT was useful for IMCR in terms of practicing elements of instrument navigation in various simulated conditions.