Interesting thread - I'm running this and have never done it before. I did do the Lakeland 50 this year, but that was part of a team with a large proportion of walking, whereas I will be aiming to run all of this (other than briefly stopping at the checkpoints), which is a very different prospect.
Matthew - to me it sounds like you're obviously a decent runner, and with a few extra months you could probably do very well, but you're running out of time now to build your endurance. Allowing for a taper we've only got about 6 weeks of training left, which is enough time to make some improvements, but not ideal.
To be honest I'm in a slightly similar boat as I haven't got around to doing as many long runs as I'd wanted (only done one over 20M in the last few months - too many XC races!), but I do have a bit more of an endurance background having done a couple of ironmans and about 15 marathons.
Dill - I'm guessing Matthew is fairly young and has competed at a decent standard in other sports. I know a few people like this and they would never do a race with the mentality of "just wanting to finish". Each to their own though of course.