Don't know about that end but whatever you do avoid Reading. Best route would be to cross the river at Sonning bridge, then skirt round the north of Caversham, then through Chazey Heath and Path Hill. It's not brilliant, but nowhere is on a Friday evening. If you really want freedom from traffic there's a fairly benign off-road route from Sonning bridge to Whitchurch, but I'd recommend at least 28mm tyres, and you will get some festival pack-up traffic along the Mapledurham stretch.
