That is quite impressive being able to play lots of football and other sports without running
Seriously I'd agree with pretty much all the above though playing other sports so close to running a marathon would not be my ideal preparation. Perrsonally I think you should put in at least one 16+ mile training run though no need to run the full 26 miles until the day. However, I do agree with Quickfire Double that at this point you need to be taking it easy though if possible I'd still put in a few gentle runs until 2-3 days before, no need to go at any great pace but just stretch your muscles.
Depending on your training/level of fitness then it is clearly sensible to run at a comfortable pace, if there are a lot taking part I'd start at the back to avoid those who go off at a crazy pace. There are always some !
Good luck !