The easiest way to get there is to fly in: the airport is right next door, literally, to the race circuit. You can fly in using Ryanair, FlyBe,bmibaby or Jet2: they all have their own websites.
Taxis around the event are expensive but public transport is excellent with buses running 24/7: Google SkyLink and check the airport website, www.eastmidlandsairport.com.
On the airport site are 3 hotels: the Thistle, Radisson Blu and Premier Inn. During the festival prices go through the roof. You can check rates on their websites. There are plenty of bed and breakfast places around but they get booked up quickly, the sooner you can check rates the better the chance of getting a room.
Alternately, you could bring a tent and get a family camping ticket for the full 5 days: last year it was £185 each.
You can walk from the circuit to Castle Donington where there are shops, restaurants and pubs: if you can put up with a bus ride, Long Eaton, 8 miles away has more hotels, shops bars etc.
If you are coming by train you can go to Derby and get the festival bus or East Midlands Parkway and get the festival bus.
Edited: 07 February 2012, 14:58