School Teachers' Pay and Conditions 2011
63.1 No teacher may be required to work on any Saturday, Sunday or public
holiday unless their contract of employment expressly provides for this.
Also relevant:
Specified working hours
62.4 A teacher employed full-time must be available to perform such duties
at such times and such places as may be specified by the head teacher
(or, where the teacher is not assigned to any one school, by the
employer or the head teacher of any school in which the teacher may
for the time being be required to work as such) for 1258.5 hours, those
hours to be allocated reasonably throughout those days in the school
year on which the teacher is required to be available for work.
62.6 In addition to the hours a teacher is required to be available for work
under sub-paragraph 4 or 5, as the case may be, a teacher must
work such reasonable additional hours as may be necessary to
enable the effective discharge of the teacher?s professional duties,
including, in particular planning and preparing courses and lessons;
and assessing, monitoring, recording and reporting on the learning
needs, progress and achievements of assigned pupils.
62.7 The employer must not determine how many of the additional hours
referred to in sub-paragraph 6 must be worked or when these hours
must be worked.
In other words, you cannot be made to work on a Saturday unless your contract says so. You can only be directed to work in a particular time and place for 1265 hours a year. You are expected to do more work such as marking, but you cannot be told when or where to do it.