The Environment Agency and the Health and Safety Executive have been working on providing guidance on dealing with asbestos measurement and risk assessment for some time, and unfortunately it seems that there will be a considerable delay in this being issued.
In the meantime, UKAS, the national accreditation body, has been making its views known on this issue, culminating in guidance issued recently. Please follow the link to a document that includes the UKAS note and a discussion of the implications.