Yes thanks Steve, that is really helpful. Access to the nest would be complicated and I think possibly expensive so unless the local beekeepers are also qualified builders I think I'll pass on that. Just wondering now if we blocked up all the air vents whether there is a possibility of them accessing the house.
I'd maybe consider letting them be (haha bee geddit) as killing them all is not a nice prospect, unlike killing hundreds of wasps - but as luck would have it, the air brick they have chosen is right outside the back door.