Where/who do you go to get properly diagnosed and treated for this sort of thing?
First, go to your GP. They’ll talk about what prompted you to go see them, and will then discuss options with you. They may want to give you pills (mine did, but I preferred not to take them), and may want to refer you to a counsellor, or psychiatrist, or some sort of self-help. My impression is, though, that getting decent psychiatric help is difficult on the NHS, unless you’re a complete basket case.
Oh – if you do go and explore this, be prepared to be completely honest, even if it’s a little uncomfortable. If there’s anything you don’t want to answer, tell them, rather than just making stuff up.