Disclosure Scotland are the relatively newly formed government agency that provide discloures to both individuals and organisations throughout the uk (not just soctland), relating to convictions under the 1974 rehabilition of offenders act;
www.disclosurescotland.gov.uk
With regard to finding out, as Kathyan said, you have to have the permission of the person in question due to data protection. The person has to apply for this themselves, or give express permission to an organisation applying on their behalf.
In any case, the report they send is always sent to the individual in questions's home to give them the opportunity to decide whether they wish to disclose this to anyone else.
The lowest level (basic) disclosure lists unspent convictions (as per the rehibilitastion of offenders act) and can be applied for by the individual or an organisation on the individuals behalf.
There are two higher levsl of disclosure which the individual has to approve but whose application must be countersigned by the organisation that requires this report - these tend to be applied for by organisations employing people who work with children or the elderly, or those appointing senior figures within companies.