If your coming from Tewkesbury i would just stick with Kemerton, You can climb from Beckford, Ashton, Emley Castle etc, but they all involve more road work to get to. Although you can ride off road from Tewkesbury to Beckford i guess. Go out through Ashchurch cross the Level Crossing, take the Carrant turning then follow the bridleway across the fields, cross the road, little bit of road, then farm track takes you to the back of Beckford. Turn left on the road, when you come to the junction there is a road left of straight on between some houses, follow that to the top of the hill.
Although depending on your mentality it is actually possible to ride off road to Cheltenham from Tewkesbury, most of the way IN SUMMER!!!!!!, or to the Cotswolds proper. i.e. Cleeve, Leckhampton, Snowshill, Cranham, etc.