latestpilotjobs.com and flightdeckfriend.com are two sources I found helpful. The various cadet pilot blogs that are knocking about also have good nuggets of info. However, like you, when I was applying to airline cadet schemes I failed a number of Assesment processes from what can only be described as "over preparation". I had spent so long practicing and polishing answers to the typical interview questions that my delivery was scripted and impersonal. Keep in the back of your mind that they are assessing your personality as much as your technical and non-technical skill set. The assessor, who will likely be a pilot or senior cabin crew, will be sat there thinking "can I sit next to this guy/girl for a 12 hour day?". This is where I fell down, but after assessing my performance and getting some interview practice I learned how to relax and deliver a good interview and show my personality and skillset.