Never bothered with aptitude testing (achieved first time passes in all ground exams, CPL and IR skill tests), if you are funding it all yourself there is little point. If your determined enough to do this and want to do this you are not really going to be deterred by a poor aptitude test result? If you do the test and get a poor / average result it is only going to affect your confidence to plough ahead with the training. So the only reason to do aptitude testing is when it is part of the selection process for a "sponsorship" scheme(eg; ctc wings, as close as you will get to a sponsorship these days).
If you can pass the class one medical and raise the funds, and have a back up plan if it all goes wrong then there is no reason not to go ahead.
Sicky; Only the integrated schools use aptitude testing for candidates as a general rule.