Regs here;
https://www.gov.uk/government/upload...14.pdf#page123
d. Non Service reasons. Personnel wishing to vacate SSFA for non Service reasons are to notify the SAT and provide 40 days notice to vacate to the MOD Contractor. Personnel vacating SSFA for non Service reasons may be required to continue to pay the SFA charge as if they were still occupying the property from the date they vacate the property until the initial 6 months of the lease has expired and/or the 40 day notice period has elapsed. A move to another SSFA for personal choice is not permitted for non-service reasons.