The Working Time Directive limits the hours you work to an average of 48 over a 17-week period. However, many employers make workers sign an ‘opt-out’ that means they can be expected to work more than 48 hours a week.
What most bosses don’t tell you is that if you’ve signed this opt out, you can tell your employer that you want to opt back in. All you need to do is put it in writing. It will take effect in 7 days time unless a different period is specified in the original opt-out, up to a maximum of three months.
The employer has no right to sack you or take any disciplinary action for exercising this, or any other rights. If they do, going to an Employment Tribunal might force them to pay modest compensation.