You poor thing. I'm a sufferer - have had it really bad in the past, to the point where I would finally get to sleep at about 5.30 and have to stagger into work like a zombie. Also had it like that when DS was young, and used to dread being in sole of charge of a baby when crazy with so little sleep.
Things I have found helpful:
A prescription for temazepam for occasional use. Sometimes you can get yourself out of a run of insomniac nights by going to bed at about 9.30pm, taking a tablet and getting a decent nights sleep. Obviously you can't do this if you have an infant unless there is someone else available to be on duty during the night.
Get a relaxation tape/hynotherapy tape. Paul Mckenna or Glenn Harrold (I think that is his name) do good ones.
Eat soporific foods as a supper snack - oats, bananas, warm milk.
Try a regime of going to bed at exactly the same time and getting up at exactly the same time everyday. Make your bed a relaxing and enticing place, nice clean sheets and comfy pillows, cool room warm bed, tidy room etc.
Don't read in bed or do anything else - bed is for sleeping and sex only (or BF if you've a little baby). Once you go to bed, if you're asleep within 30 mins, get up and do something boring like filing, paying bills, tidying etc. No watching TV, no reading etc. If you are hungry have a snack. Anything which is not rewarding you for staying up. When you feel tired again, go to bed. Do the same thing over and over until you fall asleep.
Sometimes if you're playing thoughts through your head over and over getting up and writing them all down can help.
Self hypnosis techniques of relaxing each body part can help.
In my experience insomnia is a habit, or becomes a habit, so it should be possible to conquer it by teaching yourself new habits.
Failing all else I have been known to wander down to the kitchen at 4.30am and make a hot toddy of a shot of Irish whiskey, hot milk and brown sugar. Not great but at least it knocks me out when I am totally desperate.
Sorry if you know all of this but was just brainstorming.
Good luck.