Assuming that the UK is closer to Australia than the US in terms of worker's compensation...
If you are sick, you use your sick leave. Break your leg, have a nervous breakdown, get cancer, and you are on sick leave until you are well enough to return for work...while-ever you have enough sick leave to cover the absence...three days, and you need a Dr's Certificate to justify it, or there can be disciplinary action.
Hurt on the job, there's "worker's compensation", where the employer is responsible for the leave, and the rehabilitation. Some apparently stupid things happen, such as the following article, however, the law is that you are there because your employer put you there, he get's the bill.
http://jobs.aol.com/articles/2012/12/17/workers-comp-sex-accident-business-trip/
A claim is made, supported by your doctor (and stress related illnesses are recognised), the company will then usually requested that you see their specialist, and then a return to work programme (and leave as appropriate) is planned.
There are P.I.s all over the place trying to find an employee breaching the terms of their worker's comp...e.g. finding that you are off for a bad back, and operating a lawn mowing business. Video of you lifting the mower onto the ute, bang, there's the compensation claim shot, your job gone, and your future employers notified of the issue.
In this case, he was off for stress (won't go there), was in a purposefully relaxing situation, and rescued some kids...
His bosses wanted him gone, and that's their excuse...and will be why he gets an even better payout when the courts are finished.