I'm never ill, well until earlier this year when I too picked up a chest infection. Of course I thought I knew better and thought I would be able to burn it off through continuing running. Of course it didn't work and got much worse. Ended up not being able to run for 4 weeks in February. Meant that my Bristol 10k wasn't as fast as I wanted. Lesson learned. Been building up long run steadily since then. In past 4 weeks I've done 18, 20, 8, and 20 miles early Sunday mornings and practicing fueling strategies. I'm hoping to do just under 4 hours as my first (and probably last) marathon. I think my Bristol half marathon won't be as fast as last year as I have concentrated on more mileage rather than speed work - but who knows there's still 4 weeks to go.
From the high level view the first half of the marathon - it very much looks like the Bristol Half Marathon route! which I've ran lots of times. Very flat, wide and fast. Starting @Bristol along Hotwells Road - up and over the Cumberland Basin head out a couple of miles on the Portway till you get to the first major junction turn and run back under and up on the Cumberland Basin onto Cumberland Road which runs along the "Cut" river Avon in Southville into Queens Square etc. etc.
No probs. That's landing on the front of your foot and not your heels. It took me a couple of months to adapt and it come naturally. You don't land on your toes, You try and land on the ball of your foot (the padded bits where your toes join the foot)