Getting to T5 by public transport, except by rail from central London is one big nightmare.
Sorry,
IB4138, I don't agree. If, like me, you're usually approaching from the M25, T4 & T5 are preferable to the other terminals because they avoid the M4 and the spur, which is just one more risk of congestion. If you're arriving at LHR down the M4 (e.g. from central London), of course, the opposite is the case.
If you're aiming to arrive during the rush hours, you're probably stuffed either way and then rail does look attractive, but it's not an option for me
