Check your contract terms. Normally if an employer wants to require workers to be available to work over the Christmas period and not to take holiday, this will be clearly stated in your written contract terms or in any collective agreement if your workplace is unionised.
Unfortunately, even though the Christmas period includes at least one bank holiday, there is no right to enhanced pay rates or time off in lieu for working over Christmas, unless this has been included in your employment contract. In a unionised workplace, rights to extra pay/time off on special days such as public holidays have often been negotiated collectively.
Unless the employment contract already clearly states that you must work over Christmas, your employer must give you notice that you are not allowed to take holiday over this period.
Your contract and your employer’s holiday policy probably include rules about asking for time off over Christmas, including deadlines and rota arrangements. If nothing is written down, the default position is that you must give your employer notice that is twice the length of the holiday you want to take. So if you wanted to take Christmas week off, you would need to give your employer two weeks’ notice. If your employer objects, they must give notice at least as long as your planned break (i.e. one week’s notice).
In practice, most large employers have clear rules in place covering holidays at Christmas.
There are some special rules in the retail sector, where most stores, except small convenience stores, must close on Easter Sunday and Christmas Day.