This is what an Insolvency Practitioner says about WUPs:
What can I do if we receive one? What should I do?
Other than pay up there are only a few other options. There may still be time to propose a Company Voluntary Arrangement if you act FAST....call .......
Other options include taking legal advice on defending the petition (if is not an agreed debt for instance).
If the business IS VIABLE and has a good future then administration is a very powerful means to defend the company against the petition.
Administration will “stay” (or postpone) the winding up petition and prevent a winding up order being made and any other legal action (except with leave of court).
The administrator may propose a Company Voluntary Arrangement to protect the business and allow a repayment of debts for up to 5 years. Or it may be sold to a new company or buyers (including you as directors). See the administration guide pages here.
If you decide to pay the debt, remember it will have increased because of the costs of the plaintiff (creditor).