Emergency and crisis services are largely provided through statutory services such as health and social care and might include an out of hours emergency number people can call when their GP is closed.
Your GP practice will provide you with a contact number to call during out of hours. The NHS Choices website can direct you to all medical emergency support and your local authority may have a social services crisis team to assist with other non-health related emergencies.
Mental Health crisis support is available through the NHS as well as through third sector organisations.
SANE provide a list of people to contact in an emergency
The Rethink website explains the different types of support available and how to access it and Mind provides a downloadable resource detailing who can provide crisis support and how to plan for crisis.
The Carers UK website helps you located services close to you.