Ok.. this is how it works if you are worried.
(and this is how I managed to do it, after 1 year of putting it off.. and it was the best thing I ever did)
1: Make appointment to see doctor.
2: Work out what you need to say, when he asks you whats the problem. I memorised this....
"I have been suffering from a really low mood, for the last 6 months, its has not gone away, its really affecting my daily life....."
3: Make a list of things that are going on in your life before you go.
eg: Cant Sleep, eating, people dont talk to me, no enjoyment any more.
4: Hand list to doctor.
5: He / she will have seen it all before and will suggest a course of action.
The fact that you have gone and made that step will make you feel better straight away. its your 1st step to getting out of the hole.
GOOD LUCK... tell us how it goes.