If these are records refering to you as an individual, I doubt that they still exist.
The Data Protection Act 1998 (DPA) requires organizations to only retain oersonal data they actually need. Given the length or time since basic training (especially if it was at Locking), I doubt that there is still a business case to retain the information. What use would they be now - I doubt that you would wish a desk officer or a promotion board to make decisions on your performance many years ago. If this is the case tnen your records have probably been destoyed as the law requires (the law does not permit retention 'just in case' it may be needed).
If it does still exist you can apply for its release under the DPA - see your unit P staff.
PMA records are regularly reviewed and information no longer required is destroyed. ACRs are retained throughout your career as they are used for processes such as the award of an MSM (for airmen).