There is no automatic right to Christmas day off under the law. However, there may be some exceptions, for example, The Christmas Trading Act 2004 prohibits most large stores from opening on Christmas Day.
Most people have the right to time off at Christmas under their contract of employment. Even if time off at Christmas is not specifically mentioned in your employment contract, it may be implied through custom and practice.
If you are concerned about having time off at Christmas, you should check your contract of employment to see whether it specifies a right to take bank holidays off, and also if you are required to work overtime. You must be given a written statement of your contract terms within eight weeks of beginning your job. After you have checked your employment contract, speak to your employer or union rep if you still have concerns.