If you lose the case, you can ask the tribunal to review its own decision. You must do this at the hearing or within 14 days of the decision being recorded. The grounds for doing this are limited though. Your employer can also ask for a review.
It is also possible to appeal to the Employment Appeal Tribunal (EAT), which sits in London for England, Cardiff for Wales, and Edinburgh for Scotland. The EAT is a special appeal tribunal which deals with appeals on decisions made by the employment tribunal. Appeals are only allowed on a point of law and the EAT will not normally reconsider facts already decided upon by the employment tribunal. The appeal has to be lodged within 42 days of the tribunal decision. A special form is required, which can be obtained from the employment tribunal office or directly from EAT. There is no fee.
You will need a copy of the full written reasons for the tribunal's decision, which they will send you automatically. You can also request a copy of the employment judge's notes from the tribunal.
It is possible to get legal aid for representation at the EAT and, as it will essentially be dealing with points of law, it is important to be properly represented by your union or by a solicitor. Unions may have in-house solicitors who can represent you, or may engage a solicitor for you and pay the costs.
Appeals of EAT rulings go to the Court of Appeal, but you need leave from the EAT to do this. Appeal from the Court of Appeal is to the Supreme Court. You will certainly need legal representation at these stages.
There are rules in place specifying exactly how to lodge an appeal, and you must follow these very carefully. There are also strict time limits. If you break one of the rules, even in a minor way, or if you miss the time limit, even by the smallest degree, you are unlikely to be allowed to bring your appeal.