IR35 fine - advice needed

Hi, advice needed please.

I am a locum worker working under a limited company status. HMRC investigated and ruled that I am working within IR35. I have a tax accountant that fought the case but given the case the HMRC had my accountant suggested that I accept their decision. I therefore have had a whopping tax bill/penalty to be paid back to HMRC. Going to get advice from my accountant as to what my options are..if any. I can't pay that kind of money back as my company or I haven't got it. Any help or advice please. Also noted that the HMRC say the monies can have interest added to it! - not good.

Any advice as this would be much appreciated. thanks