Coming into Coventry on the A46, take the exit marked "A45", then take the left at the roundabout. Ignore the left turning on the slip and you'll eventually merge onto the A45 west.
Turn left at the roundabout with the fire and police stations on the corners. It should be marked Canley and University.
Go straight over the first roundabout (second exit), right at the second (second exit), left at the third (first exit) and left at the fourth (first exit) onto University Road. All of these should be marked University.
The first turning on the right (Car Park 10) and third turning on the left (Car Park 4/Sports Centre) lead to car parks which should be free on weekends.