To ensure that you find the place and that you do not spend all your hard-earned cash on the trip. The best option woould be an underground (tube) train to Wealdstone or near. Ask at the station and depending on how close you are walk or phone for a taxi. If you intend to return the same way remember to find out the time of the last train back.

In truth it is not too far from where you are staying and there is probably a bus that will take you there, or close. I will give it a bit more thought too and come back.