Paying Upfront
You shouldn't necessarily totally discount the idea of paying something in advance. Although the previous posts are all good general advice, if you are going to get a good deal, and have already had a few flights, so are sure you are going to continue, also that the club/instructor/aircraft are okay, then why not pay a few grand on a credit card? If the club does go bust, then your card issuer is jointly liable and you can claim your money back from them under section 75 of the consumer credit act.