The trip is on UA miles via a Star award - the problem is that there are no longer any Star carriers flying to Bristol in the september schedules .
Birmingham was looked at and LH still fly there but there would be a 5 hour wait at FRA for the first connection whereas there is only a 2 hour one to get to LHR.
So I thank you for the advice and it looks like HEX connecting to the service to Bristol.
I am guessing that pre purchase of tickets would be the way to go -any suggestions for a website that has good prices .