I think both tom and snazz's post has merit. I do agree that the unscientifically educated like me can sometimes take this forum off-track, discussions here should really be focused on the science.
That said a lot of people go into mild depression for "fairly similar" reasons - usually stress created by the environment, and as the only environment is only within our brain - you know our brain senses and mirrors the environment in our head, which then sort of becomes a construct of what is external.
And whatever the science says snazz is right, there is a huge amount of the external construct in our minds that is basically opinion and values. Most of it nowadays greedy and capitalistic, our modern day heroes are all mighty 1% gods or the super successful that piss over everyone else. This view point that we all need to "work hard and achieve millions" before we are allowed to be happy is a common theme amongst most cultures old and new - though the conflict is of course - its not that easy.
I think what snazz realised about reality, was exactly the same as me. The world is filled with fantasies and success stories that few are bestowed upon, there are far more normal people who have to deal with reality than people living the dream. Learning to see reality for what it is can be life changing for somebody doused in capitalistic fantasies - and that does include the realms of movies, science fiction, often these are characters in improbably and extraordinary situations, achieving extraordinary goals. This does not make somebody who is depressed and lonely feel better.
So my point above is changing the way you see things is hard and crucial to recovering too, but I also agree with Tom' withdraw too much from the "fun" things in life is not a way forward either, in fact being part of something even if its failure but as a group of people is often better for mental health than being the "success" but alone and lonely.
A huge part of it for me - is accepting that you will have to play the "normal" game at some point, that means being special isn't really all that great, and doing what everyone else does isn't such a bad thing (including going to bars and getting drunk...) and can feel really good if you allow yourself to enjoy it and forget the fantasies. It will take time, but this "normal" anchor will be your best bet because its achievable.
Again I repeat that I strongly believe England at the moment is not an environment for happiness, go somewhere with more sunshine, more hope, less bureaucracy. If you have a British passport you should be able to migrate to ALOT of places.
On the medical side there are ALOT of choices too, and this is controversially wrong - but I wouldn't hesitate to use any medicine safe within reason (best with a doctor), ditch the stuff that doesn't work and keep the stuff that does. When you are mildly depressed, - anything any positive emotion or anchor is better than that greyness you are currently experiencing.
In other words you need sunshine