Thanks Gents
There is no bus service I am aware of so some element of driving is unavoidable. However I think my dad will be doing the driving. I don't want to miss out on the beer as we are in Hospitality for my 40th birthday treat.
I have been told of a place called Gunnersbury. From here you can get a tube into Earls Court.
If not then I think Watford underground station is the best idea.