Can I Appeal if I Lose My Case at the Employment Claims Tribunal?

Yes, but only on a point of law and only with permission, since you must first apply to the District Court for leave to appeal before your case can be brought to the General Division of the High Court. This means you generally cannot appeal simply because you disagree with the tribunal's factual findings or the amount awarded. Given the narrow grounds for appeal, it's worth getting legal advice on the strength of your case before deciding whether to pursue one.