You can raise your concern with your employer (they may have a policy explaining the procedure you can take). However, you do have the right to report your concern to a lawyer or to a prescribed person or body.
A prescribed person or body must be one that deals with the concerns you are raising. For example, reports of wrongdoing in a primary school can be made to Her Majesty’s Chief Inspector of Education, Children’s Services and Skills. The information you give to your employer, prescribed person or body can be done anonymously. However, if you do give your name and ask for confidentiality, your employer/prescribed person or body should adhere to that.
You should note, that if you do report your concerns to the media, in most cases you will lose your protected right.