Don't be confused by the over complication that goes on on this site - that is about selling past papers many of which have many many mistakes.
I did not find the site complicated, and did not feel that it was selling past papers to me.
Are there any sample papers for the schools that you are considering?
Is the school a super selective or does it have a catchment?
How much time do you have? Must you concentrate purely on the 11+ syllabus or can you do other work as well? Many of the independent schools have sample papers available on their websites, but the difficulty levels vary greatly.
Good luck on whatever you decide to do. There is a lot of useful information available on the website.