21/ 23 can not accept anyone who is under the age of 18 years old at the time of their application. The upper age limit for applicants is 32 years for direct entry (those who have had no previous TA or regular service) or those that transfer from other TA units. If however an applicant has previous REGULAR military service of 12 months or more, the upper age limit is extended to 34 years.
Ring your local unit for specific advice