How much does it cost by tube and mainline train between Redbridge and Brentford stations (return)?

I know that it's impossible to go all the way by tube. I believe you have to change from the tube to the mainline at Ealing Broadway.How much does it cost by tube and mainline train between Redbridge and Brentford stations (return)?
It's been a long, long time since you could get a train from Ealing Broadway to Brentford (and it would have required a change at Southall, anyway).You have to take a Central Line train from Barkingside (or whichever station is most convenient to you on that line) to Ealing Broadway, then catch a bus on route E2 from bus stand F