The minimum statutory entitlement under the EU Working Time Directive (different from the 5.6 weeks under the UK Regulations) must generally be taken during the leave year.
If you are entitled to more than the statutory minimum paid holidays then you may be able to carry the extra days forward (often called banking your leave). This depends upon your contract of employment.
There is no statutory obligation on your employer to let you carry over leave which you have not taken within a holiday year, but many companies develop their own flexible provisions for this.
You should consult your company's staff handbook or your contract of employment for the policy at your workplace.
