God bless the UK's Unfair Contract Terms Act 1977, which doesn't permit this kind of "well it's in the contract" excuse. In 2000, the High Court confirmed that this Act applies to employment contracts.
There are also laws around termination of employment in general so I think that this would be easily rebutted in Court.
There are also laws around termination of employment in general so I think that this would be easily rebutted in Court.
https://en.wikipedia.org/wiki/Unfair_Contract_Terms_Act_1977
nb: Not a lawyer by any stretch of the imagination