Army Service records are held by the MoD and are obtainable from the following address:
Ministry of Defence,
Army Personnel Centre,
Historic Disclosures, Mailpoint 400,
Kentigern House, 65 Brown Street,
Glasgow, G2 8EX,
tel: 0141-224-2023 & 0141-224-3303
Give them a call first as a fee is payable and proof is required that you are related.