Hi Dan, yes you can park on the grass by the start. Not a car park as such but lots of people always park here and it's fine. Also, there is a lay-by on the A38 by the finish that people often park in, then ride to the start. It's about half a mile from the start I would think.
If you park by the start you will have to ride back up seven stoke bank after you have finished....
If you click on tt diary on the home page, then on courses you can see a brief description of where to sign on etc..
Good luck tonight, I will be on a black Dolan with odd wheels, as I discovered a crack in my flash carbon front wheel this morning....