If coming by car, there is ample free parking in the neighbourhood.
If coming by bus, you can take either bus nr. 43 from Leiden Central Station or busses nr. 43 or 385 from Den Haag Central Station to the bus stop “Van Oldenbarneveltweg” in Wassenaar.
My office is a five minute walk from this stop.
Please check www.9292.nl for specific travel times.