SN, we all face similar pressures. At the unit where I work, we have the constant conundrum of whether to provide services to military aircraft (after all I am military) or the CAT that has chosen to go off-route (a good example is the NCL traffic which chooses to fly UL602 DCT as opposed to UY70 - UM150 - P18). The problem is that the CAA expect us to be equitable in the provision of service and we end-up working on the 'first come, first served' principle. Taking the "commercial has priority" to the extreme, you could find that Ryanair/Easyjet/BA etc would be trying to feed ATS units 'backhanders' for preferential treatment in the pattern.
Finally, I think there is a difference between defining airfield/airport utilisation/prioritisation protocols and managing airspace effectively. Bristol/Cardiff will be interesting.