Best to approach from the village of Oxenton along the track shown on the 1" OS map. A lovely little (therefore an early one?) hill fort, off the beaten path. Two ramparts visible on two of the three sides, poss a third one on the North slope. Lots of ancient quarrying inside the fort itself. Visted in May 2012.
Agree fully with Thesweetcheat, when I tried to get close to the hillfort I was confronted by a lane which led into a very, very muddy farmyard. Anyway, I think this is one of those sites which is best viewed from a distance. A good view can be obtained from just off the main road - and less muddy!!
Made an aborted attempt to visit Oxenton Hill on a bright but very muddy winter day (17.1.2010). Approached from the South along the Gloucestershire Way, via the nearby Crane Hill. Unfortunately there is no public right of way onto the top of Oxenton Hill and the mud slalom didn't encourage me to investigate further.