How much notice must union representatives give to their employer of time off required for union duties?

The Acas code of practice on time off for trade union duties and activities provides that union representatives should provide "as much notice as practically possible" when requesting time off to carry out union duties. The notice should include details of the reason for the time off. The intended location, and the timing and anticipated duration of time off required.

Where the union representative intends to undertake training, the code suggests that they should give at least a few weeks' notice of the time off required, along with details of the proposed course.