Due to an alert from another member and having done some Googling, there are predictions of huge volumes of returning traffic and resultant jams on the M5 on Sunday [and presumably also the M49/M4] as people return at the end of half term week and the 4 day bank holiday. We’ve experienced what the M5 can be like a couple of times previously when returning from Somerset, and it really spoils a nice day out to be sat in traffic jams trying to get home.

So reluctantly I have decided to postpone this trip to the following weekend, and to run it on the Saturday [11th June] as I am unavailable on the Sunday. I know a few folk have already booked, but I admit I didn’t think about what the traffic might be like. The RAC are predicting nearly 20 million road trips away this coming weekend.
Really sorry about this but I wasn’t thinking ahead, although to be fair the dates were decided on a year ago.
I have considered alternative routes back [e.g. A39 from Galstonbury, then A37 to Bristol but then there’s still M32/M4 to contend with.