I can't remember what I said in that thread, but I just googled it and found the ACAS website (they are the official body who mediate between employers and employees when there is a dispute).
http://www.acas.org.uk/index.aspx?articleid=1373
These bits seem important
Are there rules for how my working hours are determined?
Yes, the Working Time Regulations (1998) govern the hours you can work. They determine your maximum weekly working time, pattern of work and holidays, plus the rest periods you must be given daily and weekly. They also cover the health and working hours of night workers. There are a small number of exceptions: certain regulations may be excluded or modified by a collective or workforce agreement, and certain categories of worker are excluded (see Flexible working and work-life balance Appendix 5).
What are my rights to time off under the Working Time Regulations?
The Working Time Regulations provides you with the rights to:
a limit of an average 48 hours a week on the hours you can be required to work, though you may choose to work longer
4.8 weeks' paid leave a year (5.6 weeks from 1 April 2009)
11 consecutive hours' rest in any 24-hour period
a 20 minute rest break if your working day is longer than six hours
one day off each week
a limit on the normal working hours of night workers to an average eight hours in any 24-hour period, and an entitlement for night workers to receive regular health assessments.
Do the Working Time Regulations apply to me?
The Regulations apply to all workers whether part- or full-time, including the majority of agency workers and freelancers, although certain categories of workerare excluded (see Flexible working and work-life balance, Appendix 5).
So the 'Working Time Regulations (1998)' cover the law. If you google that, you'll probably find the full legislation, but I suspect that may include a lot of legal jargon.
I then found this on the same website
Rest breaks
An adult worker is entitled to a rest break where the working day is more than six hours. The details of the rest break are to be set out in any collective or workforce agreement which applies. If no such agreement applies the rest break should be an uninterrupted period of not less than 20 minutes which the worker is entitled to spend away from the work station - and not at the end of the shift.
A young worker is entitled to a rest break of at least 30 minutes where their daily working time is more than four and a half hours. If possible this should be spent away from the work station.
But then the exceptions are THIS
Exceptions
The application of certain regulations may be excluded or modified by a collective or workforce agreement. In addition certain categories of workers are excluded from all or particular regulations including those:
engaged in the activities of doctors in training, or specific activities of the armed forces, police or other civil protection services
engaged in domestic service
whose activities are such that their place of work and place of residence are distant from one another or whose different places of work are distant from one another
engaged on security or surveillance activities requiring a permanent presence - for example, security guards
who may be subject to a foreseeable surge of activity such as in agriculture, tourism and postal services
affected by an unusual and unforeseeable occurrence beyond the employer's control, exceptional events or an accident or risk of accident
now obviously they will probably try and claim one relates to them, but I doubt that it does. But I'm afraid you'll probably need professional help to confirm. I'd try the CAB.