As you can imagine with any ground located within the confines of the M25, it will be an absolute joy to drive down to south London. However, it isn't as bad as you would think as you are heading for Kingston-upon-Thames as opposed to Wimbledon - it'll still require a trip around the M25 but you won't need to penetrate London as much.
Exit the M25 at Junction 10 (yes, that means negotiating Heathrow) and follow the A3 northbound towards central London. Exit the A3 at the junction for New Malden and Worcester Park, bearing onto A2043 Maldon Road towards Kingston-upon-Thames. At the next roundabout, take the first exit to remain on the A2043 and this will ultimately lead you to Kingsmeadow.
Tools: AA Route Planner | Highways Agency
If you turn left just after the ground into Boundary Lane, it will lead to a car park bordering a small recreation ground. Check the terms before you park up, or alternatively seek street parking by turning right off the A2043 at the ground.
Station: NORBITON
Served by: SOUTH WEST TRAINS
Services to: LONDON WATERLOO
Leave the station via the rear exit upon arrival, and turn left down Norbiton Avenue. Turn right into Gloucester Road and continue walking down to Kingston Road. Turn left here, and Kingsmeadow should appear on the right. The walk is less than a mile and should be do-able in about 20 minutes.
Tools: National Rail | tubeplanner.com