See:

• Company – Defending a Claim for Unfair / Constructive Dismissal
• Company – Defending a Claim for Wrongful Dismissal

As above, with the same fee estimate for defending a claim of unfair dismissal i.e. between £25,000 and £40,000 plus VAT (currently at a rate of 20%) and disbursements, given that claims for unfair dismissal and wrongful dismissal are often brought in conjunction with one another.