Assuming you're in the Oxford that is in the UK, you certainly don't have any rights to start taking a company's property because it owes you an unsecured debt, and they'd have every right to report you to the police for theft if you did.
Essentially, if you wanted to be able to repossess the aircraft, you would need to sue them for the debt, and then use the subsequent court order and their continued non-payment to apply to court for a charging order over the aircraft, which would put you in the position of a secured credit. If you managed to get this far before the whole lot went into insolvency, you'd still then need to apply to court for enforcement of the charging order - it doesn't give you rights of repossession on its own.
Remember there'll be various legal fees involved at each stage of the above - if the company's about to go insolvent anyway, you're unlikely to see any of that back. You'd be better off trying to negotiate with them to get paid before it goes into insolvency, I would imagine.