It's really easy to get to - as has been said, it's signposted from the M6 and the M42 so you just follow the signs. It is worth checking out site and hall plans though as, in my experience of going several times, the car park people are hopeless at directing you and the signage isn't too good. So it helps to have an idea of which car parks are nearest the halls. For anyone who is disabled it's also worth getting there early as there aren't many disabled spaces, and you can't rely on the car park staff to direct you to the next nearest car park. One year I ended up parking miles away in a non disabled space (after several staff had sent us all over the place), didn't see any shuttle buses and ended up struggling through the mud to get to the halls, only to then see car park staff directing newcomers to (non disabled) spaces near the entrance.
In addition to Reynard's suggestions as to what to take, I recommend a credit card!