Hello, I'm Keith and happy to help you with your question.
In my experience I don't think you can. However, you could apply to the Court to have the case adjourned to a later date to allow the plaintiff time to amend his claim. The main bulk of HMRC's claim is perfectly legitimate, the debt is over GBP 750. There was a case many years ago when the limit for winding up was GBP 50 and someone put I think it was ICI or BP into court on a winding-up petition. Counsel for the company simply scoffed at the petition but the judge merely looked over his glasses and asked on what grounds a winding-up should not be ordered. The company settled the debt on the spot.
Your company is in very dangerous waters, even though HMRC's attitude might seem a trifle heavy handed, they are within their rights. You must put this in the hands of a competent solicitor immediately; waste not a moment or your could loose everything, at a stroke as it were.
Get round to a solicitor without a moment's delay; preferably one with an insolvency practice; it is vital.
You question keeps re-appearing, a glitch in the Just Answer system I suspect. This post is just to clear the system!