Good on you Hayley!
The trick with treadmills is to start out slowly and build up your distance and speed gradually.
Time on a treadmill can drag a bit so it's a good idea to watch TV, listen to music or regularly change your speed while your walking to keep your mind occupied.
I've got a treadmill and use it most days (particularly now that its getting colder outside), I love it!
Let us all know how you're progressing