Originally Posted by oyster
It's not THAT bad here!!!
I've done all the aforementioned options more than once and train to Clapham Junc, then train to Feltham, then 285 to Hatton X, then rail replacement to T4 will be the quickest on 9 out of 10 journeys beating the HEX route by a few minutes.
Fastest of all would be to get a cab from Feltham station to LHR T4 - this should only cost a few £ and will save the hassle of the bus change at Hatton X.
I second Oyster's comments (re Croydon)!! I spent many a year growing up there. We have a Starbucks and everything in Croydon.