Peter,
Firstly 9 min miles isnt slow.
Secondly agree with top tipsters that starting further back means you won't start with the speed kings
Thirdly doing 11 miles at this late stage will do more harm than good
Fourth start slow, and aim to stick to 9+min miling at least for the first half of the race , if you find yourself at 6 miles in 50 minutes (quick-based off your 9 mile time) you will find the run in painful.Better to get there in nearer 56-60 , so check your watch at mile intervals and slow yourself if necessary.
If you get to 10 in around 90-95 and feel good then you can enjoy the run in and the race.
Fifth, the event,the crowds, the runners and adrenalin will be worth a mile or three anyhow.
Go fot it and we expect a report on the 'events' thread in due course.
Remember above all enjoy the run.You'll do fine.