On your head be it! This post may sound angry but it is not supposed to so I apologise now.
As WWW said earlier, 500 hours of flying about in a commercial environment will send you to the top of the tree for interviews and type ratings for next spring and autumn 2006. I hope for your sake that you are not in the same position next year. 18K with a bond is not unreasonable for the experience you will get. If you work your sums, 500 hours will put you in the frame for that currently illusive jet job on a salary of about £35k with flight pay and extras taking you to about 40ish. I don't believe that the bond would warrant not leaving and paying it off. Always take the first job you are offered or why did you apply in the first place? Once you are in it is fairly easy to move about, I hope you don't stay on the outside too long. This industry is only so big, and all the training captains and fleet managers know each other if only by association. I hope this move doesn't return to bite you on the @rse.!!