Mate, without wanting to sound like a know all, I've sat aptitude tests for B.A, Air 2000, and the Royal Navy, and to be honest the tests that you can download from the civil service are, if anything easier in comparison.
The hardest thing about BA's numerical reasoning test is the strict time limit. The maths questions in themselves are not that tricky, but as you have about 25 sec per question your mental arithmetic needs to be lightening fast. Anyway this is somewhat irrelevant at the moment as BA have stopped their CEP entry scheme as I am sure you are aware.
The RAF and Navy aptitudes which ar ethe same thing contain questions very similar to those on the civil service self assessment download.
AIr 2000 tets, which again have been cancelled this year, are also just as challenging in my mind!
Sorry to be the harbinger of depressing news. but the grim reality is to get sponsorship to fly whether in the RAf, Navy, or civil avoiation you really need to be **** hot!
Good luck!