Getting information on your entitlement
Some calculations about your entitlement are easier than others
The basis for working out Basic State Pension and Single Tier Pension is relatively straightforward, but the system for calculating Additional State Pensions and deductions made for contracted out service is exceptionally convoluted.
In the government’s own words “these complex rules have made calculating or forecasting a person’s Additional State Pension entitlement difficult.”
Whichever of these systems applies to you, the following official online resources might be useful: