Unfortunately, Button Push Ignored is right, it's a BIG commitment from your parent or guardian, especially if there are trust issues. I know many parents who would not dare lend their irresponsible 20-year-old the money for a new phone, never mind put themselves responsible for £90k.
The only way to get around it would to sit down with your parents, and effectively give them a sales pitch or business plan, along with a contingency plan if anything goes wrong. I.e to explain to them that you will finish your training after 18 months, and you will then have 18 months to find a job, after which the payments of £850 per month will be going out, whether you have a flying job or not. You'd have to convince them that even if you don't have a flying job within 18 months, you WILL go out and work, doing whatever it takes to make your repayments. They need to genuinely trust you with their lives and their livelihoods, it's not like you're babysitting the dog.
