Transfer values are only available to "deferred members" of schemes. This means you've left the company, or are about to leave, but have yet to start your pension. Once a final salary pension is in payment it cannot be transferred.
The transfer value will depend on your age, the level of forecast pension when you retire, your retirement date and how generous the annual increases are on your pension both in deferment and when it gets paid.
New proposals have been made to permit any unused drawdown account to be passed on free from inheritance tax when you die.