” When agreeing to be furloughed the company said they would be using the average of the last twelve months option to calculate as obviously our wage fluctuates each month.”
Ok well if they told you that’s how much they were going to pay you, with no caveats and no conditions, that’s what you’re entitled to receive.
”Now we're being told with very vague reasons it might not be possible for the co to claim it”
That’s not your concern, unless they’ve put a condition in the furlough agreement that you will only receive that money if the company can claim it back.
”I've asked if they've tried and been met with a don't know and face potentially having to pay back the furlough money I've received in my pay for the last 2 months, they'll just take it out my next 12 months wages so I have no way to stop them”
Furlough money is what the employer claims back from HMRC, it’s not a payment you are or are not entitled to. You going on furlough and receiving 80% of your pay is a contractual thing agreed between you and your employer.
As per usual, if your employer doesn’t pay you what your contract/other relevant agreement says they’ll pay you, it would be an unlawful deduction from wages.