In reply to Coel Hellier:
> Go to the darkest site you can (no moon as well as no lighting).
> Set ISO fairly high (though perhaps not the highest setting).
> Put on the widest-angle lens you have, and open it to the widest stop.
> Expose for 30 secs (use a tripod or put the camera on something).
> See what happens, and then experiment a lot from there.
Cheers, looks like I will be aiming for a few trips to Northumberland and Kielder this autumn and winter