"The inevitable tax bill" if you are declaring your income to HMRC will never come. If you are paying honest income tax based on your gross income and claiming only provable,receipted expenses, together with social insurance (in many cases both employer and employee!) you are going to have no problem.
It is the employer who commits the offence in this case - whoever that is found to be.
There are plenty of people just trying to pay fair tax and earn enough to pay the mortgage who should not be lumped in as avoiders who deserve what is coming to them by the likes of the Count who is lucky enough to be working for plan Orange rather than the Harp.