Here's another route via Fox's Diner. Start at the lay by on the A355 (Slough) to the A413, onto the 329/4074 to Fox's. Back via Goring, the A329, A33 and 272 making your way back to Boxhill.
I've done it a bit at a time but never got round to doing the whole thing. Must put that on the list of to do's.