It is worth searching under BA aptitude tests, and you will be surprised all the info there.
However if it helps, the GMAT book is very useful. You will have to answer about 40 questions in 25/30 mins, all answers either true, false or can't say. If you learn the principles from GMAT book, you shouldn't have a problem.
It is also worth reading, not flicking through, a good newspaper. Try and get into the author's mind and see exactly what they are saying.
Hope the above helps in some way.