I don't think there are any experts in UK employment law here.
If you are a union member, talk to your union rep. Otherwise, try talking to ACAS (the Advisory, Conciliation and Arbitration Service) and your local Citizens Advice Bureau (CAB), which provide free employment advice.
As I understand it, your employer should have considered the ACAS code in coming to its decision. You may be able to appeal your employer's decision by writing them a letter asking for reconsideration, or submitting a complaint to an employment tribunal. Frankly I wouldn't hold out much hope, but you never know. Go talk to ACAS.