Wood workbench as ESD protection?
Bare wood is a reasonably good "antistatic" surface.
I'd expect it to probably be safe but characteristics will change somewhat with timber type, degree of dryness etc. 

For added confidence and/or a perhaps 'flasher' look, you can use butyl-rubber sheet (BRS). BRS is used for roofing and tank construction and various impermeable barrier applications and is relatively cheap. When shipped to larger resellers they may use BRS out packing around the whole bale and they generally sell that at a much lower price than the 1st grade product. I have used BRS bale outer wrappers as anti-static surfaces for many years. outer 

BRS is bulk conductive due to the embedded carbon black which is used to colour it.  You can probably rely on it being antistatic without testing but a test can be carried out by:


Set multimeter to a 1 Megohm or more Ohms range.
Press two probes into the rubber so that they deeply indent or penetrate the surface.
Have probe tip spacing as small as possible without probes touching.


If you get ANY conduction at all the BRS will work as an anti-static surface. You can apply a ground clip to a corner or edge, but just laying on a wooden bench top should work well enough.

Note that if you use equipment with high voltage between terminals which both touch the sheet you may get conduction and bad things happening. Ground leads whether for the BRS or user ground straps or other ground anti-ESD connections should use say 1 megOhm series resistors to prevent high-current flows in case of accident. If you use a hard grounded wriststrap and touch live mains then it is easier to die than if you are not hard grounded.