Hi, you are going to have a great time! The people are great, the beer is stronger than over there so you best get some practice in!!! The weather will be beautiful British summertime!! Where you staying, at Donnie or in a hotel/B&B? Are you going to have a bike over here to play on?
You can get there from london in about 13/4 hrs - I would aim to be there by 7.30 at the latest - you'll probably still have to queue from the motorway.
By the way - if you get directions from the internet, make sure you spell it with one 'N' in the middle - I live in Donnington (with two Ns), and although you won't have to queue to get into the village, you also won't see any racing.
Have a great day - I can't go this year as my second child is due right about the same time.........I usually camp from thursday to monday, which is the best value (£69 this year , I think)
If you do stay in Londan try to be in the north of the city preferably near the M1 motorway You can waste an hour navigating trough the city although Sunday morning wont be bad for traffic try looking for a Novotel or travelodge which you may find next to the M1, this road will take you all the way to Donington following signs for the East Midlands Airport. I would suggest you are on the road for 4AM which will leave you plenty of time to get there and possibly aviod any traffic jams.
Craner Curves is a very good viewing spot either on the inside or outside the the track