Good Lawyer Guide's response

Yes. The law says that you have to give notice that is twice as long as the amount of holiday you want to take. For example, if you want to take ten days leave then you have to give your employer 20 working days notice beforehand (note: 20 working days is going to be four weeks, if you work five days per week). So if your boss insists, then you may well have to give notice before taking your holdiay.

In fact, the situation can be even worse than that. Employers are allowed to lay down an even longer notice period in the terms of employment (which you should have a copy of). So, for instance, an employer could insist upon three times the amount of notice! Having said that, the courts have made it clear that employers cannot use any of these notice rules unreasonably, in such a way that would effectively defeat your entitlement to annual leave. So, if you are met with a blanket refusal – without the employer giving it any thought – then that may well be unreasonable. On the other hand, if the employer thinks about it, and decides that you having time off would cause staffing problems or difficulties, then it will probably not be unreasonable for him to insist upon the notice rules.

Another point you want to remember is that the general rule with holidays is that you must ‘use it or lose it’. This is because you cannot normally carry holidays forward from one holiday year to the next. Unless your employment terms say otherwise, holiday has to be taken in the holiday year.