If your employer wants to rule out some periods for holiday requests, you must be given notice of this. The notice required is the same as the period during which holidays cannot be taken. In other words if the employer wants to stop people taking holidays for the 2-week period between Christmas and New Year, then 2 weeks notice of this must be given.
If you are requesting a holiday, you must also give your employer sufficient notice. This must be twice the number of days of leave that will be taken. So if you’d like to take 4 days holiday, you need to tell your employer at least 8 days in advance.