Use the minicab drivers route, up over west norwood cross leigham court road, cross Streatham High Road, get onto tooting bec road, cross Balham high road on to trinity road over Wandsworth bridge, left on carnwath road past hurlingham club onto munster road, fulham palace road and on to the A4 at Hammersmith. From then on its a doddle. Should be an hour or so if you leave before 7am.