Bristol Forum: Dog-friendly pub accommodation close to M5/Bristol area

We'll be driving from the Isle of Man to Devon in May this year and are looking for a place to break the journey overnight. In the past when we've headed down to Cornwall we've stopped in the Gloucestershire area, but this year it seems the night we want is when there's a big flower show on in the Cotswolds and everywhere I've tried has been booked up. So I'm wondering about around the Bristol area instead? Ideally looking for a nice pub with rooms that will take a well-behaved Border Collie, not too far from the M5 but in a quietish location where we can exercise the dog nearby. Any suggestions would be appreciated, thanks!