Herod - wef 1st September 2012, UK CAA began to accept SSRIs as an acceptable medication under EASA regulations.
There is a Depression flowchart to follow on CAA website which offers full guidance.
It is worth noting that an employee can be dismissed on ill-health grounds, even if they hold a valid sickness certificate from a Doctor. This would be done on Capability grounds at a formal meeting with HR, Union Rep. etc.
Unlikely to be mentioned whilst employee was still receiving Company Sickness Benefit, unless they had specifically requested a severance package on grounds of ill-health.