Posted: Yesterday at 09:45
that's a lot of questions! Here's my take on a few of them, but I'm sure there may be differing opinions.
Time vs distance: different philosophies for training and potentially depends on the target audience, as elite runners would cover bigger distance in the time period ( so a one hour run could be 10 miles for an elite, whilst it would only be 5 miles for a slower runner). Both systems work for some people - so its your choice which approach to take.
Sore back: It would be worth visiting a physio or sports therapist for a physical exam, but it is definitely worth adding some core strength into your marathon training.
bathroom: you said you were drinking water constantly - don't drink as much and see what happens. Do you take drinks during long runs? experiment with drinking at set intervals (e.g every 3 or 4m) during training. You should go into the race having a good idea of how often you will take a drink, and have practiced this in training. This is especially true at London its very easy to drink too much as there are water stops at every mile. NB You have to be sensible - if its a hot day then you take water from a few extra water stops - but you definitely don't want to take 26 drinks!
3x a week training: the more training you can do, then the better your result. If you want to make a significant improvement to your time, then you need to find time for more training. However, it is a balance between running and other commitments, and there are three day a week training plans, have a look at: