I hope this will be of some help and not confuse things? I too have a Mental Health background, mostly in crisis intervention both community based and managing units. I did have a career shift a couple of years ago, but am still within the social care field and recently had to move to find work after redundancy.
I have found that some organisations I have worked for do not take account of covering letters when they ask for a CV/Resume.
The advice I had was to put a "personal summary" as the first heading on a CV. Mine is eight lines long and covers who I am and what I have (recently) done. It took me about four drafts!
I personally think that giving someone a real feel for who you are at the outset (especially in mental health) is important. If you make it obvious that you genuinely value people and have the skills to help them no one (worth their salt) will give a stuff about your age.
Good luck and positive thoughts your way!!