If your working conditions are intolerable, your options include:
There have been some well-publicised cases, with large payouts, but do not assume that all awards are easily won, or very large.
If, after a long spell away from work, your employer fails to make 'reasonable adjustments' to help you return, you may also be able to take action using the law preventing disability discrimination, which is now contained in the Equality Act 2010.
24 Feb 2012: When do you start getting paid?
The Interns: Getting treated like a dogsbody?