Parking at Dover port

[BMGM3]

Need to meet up with a mate at Dover port, but he'll be needing to park the car there somewhere,ideally in the port while we go in my car for a few days at the Nurburgring.

So does anyone know if they have a large car park where he can leave the car for a few days, and if there is one , any idea of cost or where it is located within the port area ?

Thanks !