Hi Craig,
Welcome to the club.
I would have a good look around the car before you go home, and then have a good listen for it again. These types of things can be quite frustrating to find, but hopefully it will be something like a small branch covered in dry leaves. Have a good look under the car, there may be something wrapped around an axle.
How old is your car? Could it be a bit of dust on your brakes? Hand brake slightly grabbing? Have you noticed increased fuel consumption?
FatBoy
(currently in Aberdeen, just up the road)