Just thought I'd add this.
As stated in a previous post I was told to write to the SPVA to get a pension forecast prior to leaving. I did this as I needed an accurate forecast.
The reply I got simply said, please use the online pension calculator which is as accurate as it gets. I know this not to be true because the online pension calc does not take into account the new DIN.
Put simply it is worthwhile writing to the SPVA if you are already out and require annual updates on your pension but don't bother if you are still in as they are pretty useless.