Thanks for all of your replies. I think I will continue to monitor HR but not get too obsessed with it. As many of you stated I am new to running and still consider a 15-mile week very good! I will build this up to 20/25/30 etc and I'm sure things will continue to improve hopefully.

I did a 10k race yesterday, and finished in 62 minutes which I'm really happy with. I went all out: Heart Rate was pretty much 170 for nearly an hour.