Well, I went out and completed the first run of week 5 earlier this evening without any problems. Again, the only concern I have is my lower legs felt really really heavy a few minutes after starting the actual running but as soon as I go back to walking they feel ok. My breathing is not causing me any concern at all, as I recover as soon as I stop running, so that's a good sign.
I managed to find a totally new route to run today as well, and it was ideal...I parked my car next to the park in Lethlean Lane in Hayle and on the other side of the road was the entrance to a wide pathway that lead all the way down to the start of King George V Memorial Walk. It's nice and flat and follows the estuary down to Hayle Harbour past an outdoor swimming pool and cafe then joins the south-west coastal path. I went all the way down to the harbour, turned around and made my way back to my car and it seemed like it was almost timed to perfection because I ended my cool down walk approaching my car!