times123 - if you find aviation "interesting", but have not really considered it, it is not the career for you. It requires dedication, and you must really be sure that it is the career for you, rather than one of a few options.
Bottom line is, you should spend some cash on a PPL separately first to ensure that it is the career for you, and that you can really stomach the flying!
I am surprised you are weak at mental maths having been in a bank, and yes, it could be a considerable hinderance if you are unable to do it. Another reason to do the PPL - this being also you best aptitude test available.
Take the GAPAN aptitude test as well.