Monaco Run!

So in November I signed up to a 15 mile run in Monaco on March 17th. I think maybe the hormones hadn't quite settled back to normality after pregnancy because I don't know why I thought that 3 months after having a baby (emergency c-section) I'd have the time, energy or ability to train for a 15 mile run! But there was method in my madness, I wanted to lose a bit of baby weight and feel fit again, so I figure its good motivation and the fact I had to book flights and accommodation i wont back out! I will admit I enjoyed running before I got pregnant with TJ but I was no Sonia O Sullivan! The furthest distance I had ran was 10km, but my norm was maybe a 4k run 3 to 4 times a week. So with a month to go until the race (march 17th) I have some serious training left to do! Before Christmas, with the initial excitement of signing up training was going great and I even started to think I'd aim to complete it in 2 hours! However the motivation began to dwindle in January and with a very busy month (Christening, Sister home from Oz) training took a backseat! So the longest run I've done, last week was 10 miles but it did take me almost 2 hours! I've to try find some hills too because the course is very hilly! Hoping to go for a 3mile run this evening that has some hills. Have you any tips for training or preparing for a 15mile race??