You will need to go through each possible airline combination that you can use those points/miles with, looking at all potential routes then search for award availability through the appropriate website - Etihad.com for EY, BA.com for most oneworld carriers.

For example with AA you obviously have EY and oneworld partners, although probably want to avoid BA due to their carrier surcharge. AB is an option via Germany, QR via Doha, etc.

Wikipedia is usually a good start to find all the airlines serving an airport. BRS is here: https://en.wikipedia.org/wiki/Bristol_Airport
Look from AUH, to LHR/LGW/LCY/BRS and then all potential transit points.