Mileage Buildup

Hi, I have been doing some short and easy runs this week after my 5k, saving a long run of 6 miles for tomorrow or the next day and will hopefully meet my goal of 14 miles this week... with a 6 mile and a 3 mile at the weekend -
I think i have recovered from my 5k last Sat now.
I have had some ankle pain but not a lot, and it's mostly been when i'm not actually running - and then only little twinges... I saw physio and she has given me extra build up for my shoes at the heel to see if that helps and i think it has helped a lot!!!
My marathon build up schedule is about 14 to about 25 miles per week then goes on to official marathon training...
I am only going to make an attempt - and if i get knocked back i think i will take it well - and just go for halfs until the year after next.
The thing about my mileage buildup and marathon training schedule is that it leaves No room for injuries or set backs or holidays and if I am going to take it seriously at some point for next year everything will have to go right... so if it doesn't I hope i won't feel like i have lost much.