Oo-er Jen, are you going to beat Wants to it?
Fluffy, how exciting about the scan next week! 
Will you find out the gender, or will you be having an UBB?
I had exactly the same problem as you hip wise on and off. I found a combination of things helped, including a huge body pillow (got mine from Mothercare) which I'd partly lean on, sometimes put between my knees, sometimes under them etc was very good. I ummed and ahhed about getting one, but in the end DH convinced me too, and I think it played a huge part in getting me comfortable at night (not that that helps the pregnancy insomnia!). At points where my hips really hurt against the bed I found putting another normal pillow underneath them helped too - just cushioning everything a bit. I think mine is due to the exact same thing - I always used to sleep on my back or my front.
Sadly I'm now at the point where so many bits of me ache that no number of pillows help!