Hi!!
Think you are definitely suffering from insomnia and it probably is because you have started a new job. I think the best thing to do is not worry (funny, I know, thats what we all do!) about the fact that you aren't sleeping. Your body will cope without the sleep and rest when it needs to. You can easily get caught in a vicious circle of worrying about it and consequently not sleeping. I think you just have to accept that you are having a few sleepless nights but that they are temporary. When you find you can't sleep, get up and grab a book or watch the telly, don't lie there tossing and turning. Just think, Oh well, I'll sleep when I'm good and ready, this won't last forever. Don't eat too late, try relaxation exercises in the evening. Snuggle up on the sofa. Try camomile tea to soothe you (sweeten if necessary) and distract yourself from worrying about sleeping. You could try herbal remedies but I think the main thing to do is to accept that you may not sleep for a while until you settle down a bit.
I hope this helps.