The A43 is very close to the circuit so you could always come off the A43 and turn towards the village, drop off along there then the driver can get straight back on the A43 
Like someone else said above, if you take the dual carriageway that leads upto the circuit and past the main gates you keep going and come to the last roundabout, you could just double back and drop off there 
Getting out and picking up will be a different story, complete nightmare 
If your a fast runner get out as soon as you can 