Thanks for writing on my blog! Nice to hear from you. You asked about London's weather...this is London UK, Great Britian so it can vary. One year it was HOT....near 80F...one year it did everything from rain, to hail, to sunshine and temps in the 70s. Another year it was mild with cool rain.. so since it is held at the end of April... weather just depends which way the wind is blowing and if the sun is shining... It is a pretty flat course with the highest part being the incline up Tower Bridge...(view is amazing!!) Downhill bit for about first 3 miles. The finish can take your breath going down the Embankment towards Big Ben and then taking a right onto Birdcage Walk passed Parliment on to Buckingham Palace.
It is better to eat smaller portions several times a day rather than just breakfast lunch and dinner. Also, it is very important to have a good breakfast. It is good to start out the day with a good shot of protein to get your metabolism going so you can burn a lot of calories during the day.