Mind have put together useful guides to explain the Mental Health Act 1983, Sectioning and Independent Mental Health Advocacy. Please follow the links below for more information:

Mental Health Act 1983:

What is the Mental Health Act 1983, what does it cover and what are my rights? - What is the Mental Health Act 1983? - Mind

Sectioning:

What is sectioning? - Sectioning - an overview - Mind

Advocacy Service:

What is an Independent Mental Health Advocacy Service? - IMHAs in England - Mind