The average work week is somewhere between 35 and 40 hours. Luckily, many progressive countries have labor laws that prevent employers from working you to the bone with 12 hour days all week long—but what if you could opt out of that protection?
The British employers can't force any adult to work more than 48 hours a week on average. Of course, there are exceptions to the rule depending on the job. Jobs where the worker is in control, the armed forces, emergency services, and security or surveillance employees are all exempt from the cap. Places that require 24-hour staffing and people who work on boats are also subject to a longer work week.
Energetic workers over the age of 17 that want to work over 48 hours may do so. This could be for a set period of time or it could be indefinitely, but it must be voluntary and in writing. Employers can't ask their workforce as a whole to opt out, though they can address individuals.