"I did 15 miles in total last week so my plan is 16.5 miles this week (using 10%) rule with my long run at the weekend being 6 miles - does this sound sensible? Should I do more/less?"
Sounds very sensible to me especially after the knee .... this brings me onto the next thing, stay away from hil reps for a bit until the knee is, as sure as we can be, 100%. It is not necessarily the running up that only causes the problem but the running down again and to deliberatley repeat this at this stage of your training with the knee as it is is not wise. Dont worry, hills will appear
Nutrition is very personal and does need lots of practise, best thing for you is to look at what time MK starts and have a couple of practise sundays where you get up, eat porridge/bagels/full english etc, whatever you find suits you at the time interval you will have on the day of the marathon, often best on race days so the nerves kick in as well.....You can run marathons on just fluids, lots of people do, me included, but it may pose more problems than it solves with all that fluid sloshing around. All I can say is practise what you can and cant eat and when you can eat if... before and during.
Your body if you are eating properly should have enough energy for about an hour to an hour and a half of exercise before it starts looking for other supplies so your shorter runs early mornings you should be fine.but this is an oportunity to try small amounts of different stuff. people will give you millions of ideas... my own personal food is.... Three weetabix, semi skimmed milk, a bagel with peanut butter, couple of cups of coffee then glug a 500ml bottle of sports drink on the start line, butt hat works for me....