My wife and I went for a cycle yesrterday and found a great section of the national cycle network. You may have been on the M5 on the Avon bridge (between J18 &19) and seen all the 1000's of cars parked up near the docks. There is a track that runs right alongside all that, that eventually either ends up in Pill (Pill, Pill I love thee still. Wurzels) or by the river. The whole length of the track runs in a wildlfe corridor that was created. We saw all sorts. The high light of which was a King Fisher. All this and right in the middle of heavy industry on one side the M5 on the other. Probably not the most pituresque wild area in Britain but certainly interesting.
You can find the start of the trail off the Sheepway (if you know the area you will know the road I mean). You can find it in Google Earth at
51`28'49.83"N 2`43'46.13"W