There are some national domestic abuse organizations which are really useful resources for you and your clients and are a good starting point to find more local resources:
http://www.refuge.org.uk/
http://www.womensaid.org.uk/
For specialist provision for black, minority ethnic, and refugee clients, Rights of Women offers some excellent publications and an advice line:
http://www.rightsofwomen.org.uk/
Newham Asian Women’s Project also has some excellent resources:
http://www.nawp.org/
In terms of provision, there are many gaps in provision for those seeking help. To look at the issues surrounding the provision of services try the ‘Map of the Gaps’ at https://equalityhumanrights.com/en