I did the BQ last week, all I can tell is. You need to buy Skytest, I didn't and I failed miserably. Tbf I think even if I had bought I would still have failed, the test is extremely difficult, specially the mental maths part. From the 20ish people who did the test with me about 4 passed. I am still recovering from the shock. It feels like they want astronauts rather than pilots. Don't get me wrong, I think they are right in filtering as much as they can as the surplus of pilot is huge now.