You are in a similar situation to myself, if you served between 1953 (I think) and 1975 without doing full time you get nothing, there have been various campaigns to try and get this altered but they have had no result. No doubt Vauxhall can give you chapter and verse.
Prior to 1975 there were no rights to preserved pensions in any public or private pension schemes. Most schemes had very restricted qualifying criteria for the award of pensions. For instance, to qualify for a pension under the Civil Service arrangements, an individual had to be over age 50 and have served for ten or more years. Those who left voluntarily before meeting these criteria lost rights to pensions. For the Armed Forces occupational pensions were awarded only if a member had completed at least 16 years reckonable service as an officer or 22 years reckonable service as an other rank. Reckonable service is paid service after age 21 for officers or after age 18 for other ranks.
Engagements for shorter periods were on non-pensionable terms.