Hi Holly,
I too do a very stressful job, with long hours (12 hour+ shifts) and antisocial hours, and I'm finding it very hard as well. I'm not sure I have the greatest coping mechanisms, but I have tried to find a quiet corner for a snooze when I'm really dead. I'm 8+3 so I'm in a similar situation to you. I've got a week of nights coming up (5x12 hour night shifts) and I'm dreading it.
I've found eating little and often has helped, I started out eating loads of biscuits but my gp told me off as I'm already quite overweight, so now I'll have a piece of fruit every couple of hours or something like that if I'm feeling really bad.
I also got some ginger capsules from my local health food shop which have helped with the nausea. Of course that could just be a placebo effect, but hey! Who cares?
Keep your fluid intake up to help your concentration, and keep a banana or something on your desk and have a bite every hour or so to keep your sugar levels pepped.
It's rotten really, because of course if you're like me, you're probably not sleeping brilliantly either, what with peeing all night and crazy dreams waking me up. Keep your pecker up, you're not alone. We'll just have to dream of what it'll be like in four or five weeks when this has all passed, but for now console yourself that it's a good sign of a really strong pregnancy.
I hope you feel better soon xx