Neil - A44 all the way from Oxford to Worcester isn't too bad (certainly better driving than sitting on m/way and dual carriageway).
I prefer to take the A40 out of Oxford then turn off at Burford, take the A424 to Stow-on-the-Wold, then the B4077 to Tewkesbury. From there it's a short hike up the A38 to Malvern. There are fewer speed limits on these roads, less traffic, and better pubs. The B4077 is a particular favourite.
