I have a BSc in microbiology and wants to become a medical laboratory scientist. Can a MSc in CLS help me achieve this. If not what additional program do i have to undertake. Thank you.

Probably, but check with a careers adviser. Contact the Public Health Laboratory Service to ask what qualifications they want their staff to have.

If you want to be state registered as a Biomedical Scientist you need to make sure that you take an accredited course.

For example, Napier University (Scotland) do an MSc in Biomedical Science which, I believe, is accecpted by the Institute of Biomedical Scientists (IBMS - the accreditation body for medical lab workers).