Hi
From their website:
The main site does not have a direct postcode but the one below is for the NCP car park directly opposite. If you are using Satnav or working from a map, use this postcode to get you on to Garrard St and then follow the last steps on the directions below.
NCP
Garrad St
Reading
RG1 1NR
After you turn right onto GARRARD STREET – You will see a large office building immediately on the left called Xafinity House. The parking is located at the base of this building and a member of Zed staff will be there to let you through the security barrier. The actual site entrance is located 70 yards further down the road on the right. You will see a large building on the right with green wooden boarding saying ‘Private Parking’. The site entrance is between the wooden boards, through a set of large, black metal doors.
I've only played the once there, but from memory you drive past the NCP carpark which will be on your left and the mall carpark will be on your left as well about 100-200m down the road. There was a marshall directing people parking.
Cheers
G