All:
Thanks for the replies. In case of interest, wireworks is still taped off, as is the Abbey car park. Didn't cycle to Shorn Cliff as didn't want either to leave our bikes by the track or carry them up over the boulders. In the end we drove to Tintern, parked at the old hotel as Mark suggested, walked in, and had a really nice afternoon in the Fallen Block/Organ Grinder area