It is not possible to create emergency corridors in towns now as councils narrow roads and implement traffic restrictions ready for congestion charge scams. I often sit on a main road in which emergency vehicles get stuck with the rest of us due to high kerbs, narrowed lanes, paved areas with daft planters where lanes used to be etc. There was never any consultation apart from the "you say, we don't want to listen" types.

First off try travelling in the correct lane.