The value of the fund (or "pension pot") is ignored altogether as
capital.
If your customer is over 60 and is entitled to draw a pension from the
fund
you should treat them as having an income from it, what they would get
if
they were to turn it into a regular income.
You can calculate the amount of this "notional income" using the table
here.
In order to use that table you will need to know the current "15 year
gilt
yield". This is an interest rate widely used in financial calculations.
You can find this in many places online, such as
here.