You need to ask the scheme provider, not AB, because different rules apply to different schemes from different providers.
Since you input the money into this scheme 15 years ago, the Government has changed many of the rules about retirement age. Scheme providers then changed many of their rules. One of the rules related to the age at which you draw down a private pension - which was changed to minimum age 50. You may well find, therefore, that you can draw the pension early, but you need to check the details and implications. You obviously won't get as much per month doing this as if you were to retire at your normal age of retirement.