I didn't have a PPL, but did attend a local flying club who took me through the workings of an aeroplane. Did open a physics book for the first time in some ?? years, and studied recent events within the airline industry. I passed! Start Sept 08.
Just prepare, as the Assessors are only looking for someone with some knowledge and a little common sense.
Relax and do the re-take. It's not the end of the world failing. If you want it enough, you will get it!
Good Luck!