If you like I can arrange for a car to meet you at Gatwick Airport and bring you to the Guest House.
A standard car is £65 for up to 3 persons.
An Estate car (station wagon) is £70 for 4 persons.
From the Guest House to the airport is £5 cheaper.
The alternative is at Gatwick Airport to take the London Bridge train (that goes to London Bridge station). At London Bridge take the subway (Northern Line - Edgware branch) directly to Golders Green station. From Gatwick to London Bridge the fare is £10.00 one way but you can buy a One Day ticket for the journey from Gatwick to London Bridge which includes a One Day Travelcard for the subway for only £12.00