Mental health and therapy.

I've had a problem for a while with my mental health. Randomly getting really depressed (generally in the evening and I'm sure its not random, but I've no idea why), dealing with stress in pretty bad ways (cutting myself and isolating myself from others generally), and suicidal thoughts occasionally.

I want to go to therapy, but I'm really worried about it. My family can't know about any of it (I'm 18+ so hopefully that's not as issue anyway), and I'm really worried about being put in a psyche ward because of the self harm and suicidal thoughts. I really really don't want that to happen. What should I do?

Edit: Should've mentioned, I'm in the UK, probably moving to Ireland in August though.