This is a mistake! There is something like "community based psychological therapies" which will be long term talking therapies for people with severe MH problems.
But there's also therapies available under something called IAPT - improved access to psychological therapies. Your local primary care trust should have something called a PCAT (different name in different areas) - PCAT is primary care and assessment team. They have publicity names - so in Gloucestershire they're called "Let's Talk".
PCAT take self referrals, so you don't need to get access via your GP. But you can ask your GP for details if you want.
There are a bunch of therapies. I'm a fan of CBT. This is not medical advice! I'm not a doctor, and have no qualifications. I think a good working relationship with the therapist is important.
You can also get private therapy. Check for BCAP registration.
Short version:
1) Ask a GP at the surgery where you're registered for information about the local IAPT services (or do a web search for them)
2) Have a look at MoodGym (https://moodgym.anu.edu.au/welcome) or some books. "Mind over Mood" is often recommended.
3) Consider private therapy. BCAP registration is good. CBT is good. £30 to £40 per session, for about 8 to 12 sessions, seems good. (Depending on area and stuff. )
Please feel free to email me if you want. And good luck!