It is very unlikely you will be affected by the GMP test. This is because in the vast majority of cases, a civil service pension generally provides a pension above the guaranteed (GMP) level.
Once you have made your pension choices, in the unlikely event the GMP rules apply to you, the Scheme Administrator will advise you and will give you the option to re-visit your choices.
As of 6 April 2016 the Civil Service Pensions arrangements are no longer contracted out of the additional part of the State Pension. This is due to the introduction of a new single-tier State Pension scheme for people who reach State Pension age on or after 6 April 2016.
HM Treasury will be addressing the implications of changes resulting from the introduction of the new State Pension for members of public service pension schemes who have a GMP. For more information on the changes affecting GMP please visit: https://www.gov.uk/government/consultations/indexation-and-equalisation-of-gmp-in-public-service-pension-schemes
alpha benefits shown on your quote will contain all pension earned and projected to be earned up until your last day of service. The projected pension earned should only change if you have a change of circumstance between the date your quote was produced and your last day of service. These changes could be the opening or end of an allowance payment and/or an increase or decrease in your pensionable earnings.