and that's because you have to refund Flybe the 19.8k they lend you out of a 24k salary (BEFORE TAX!!!),
You seem to be saying that paying back the loan "BEFORE TAX!!!" is poor arrangement. Actually it is far better than paying it back after tax. To pay back, say, £4000 per year before tax you have a salary reduced by £4000. To pay back £4000 after tax (and NI contributions!) you would have to earn something like an additional £5500 or more!