Woodbridge Meadows has a small car park close to these co-ordinates. You could park there if you like but during the day there is a fixed charge (it is currently £4.00 Mon-Fri 08:00-18:00). Instead you could park for free in Woodbridge Road (see the suggested parking co-ordinates). Then follow the footpath that runs alongside the cricket pitch at the base of the railway viaduct, and use the footbridge to cross the River Wey.
The cache should be an easy find but may need some stealth.