Posted: 02/03/2015 at 09:12
You can only do what you can do! You trained, you picked up an injury; move on!
The most useful effect of the 20 miler is finding the right pace, but getting the pace right can be achieved without the long run. You will be surprised how slow you can go in the first half of a marathon and still finish well.
Stick to your plan, don't injure yourself and don't spend time worrying about the difference between 18 and 20 miles! The more you think about it the bigger the problem will become in your mind!
Good luck on the 22nd, hopefully there will be good weather, because I have entered the Reading Half myself!! Doing a few miles before and after the half is good advice though!